Eeschema hangs when remapping symbols (lp:#1812992)

[Original report](https://bugs.launchpad.net/bugs/1812992) created by **Frank Severinsen (shack)**
```
Hi

When trying to load a V4 project, I get the "remap symbols" dialog as
typical.
When I press remap symbols, the Project Rescue helper shows up, but I cant
press anything.

I'm not too familiar with GDB, but if I understand it correctly the output
of "where" is the needed part for debugging hangs.

Application: kicad
Version: 6.0.0-rc1-unknown-bb2e402~84~ubuntu18.10.1, release build
Libraries:
    wxWidgets 3.0.4
    libcurl/7.61.0 OpenSSL/1.1.1 zlib/1.2.11 libidn2/2.0.5 libpsl/0.20.2
(+libidn2/2.0.4) nghttp2/1.32.1 librtmp/2.3
Platform: Linux 4.18.0-13-generic x86_64, 64 bit, Little endian, wxGTK
Build Info:
    wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 2.24
    Boost: 1.67.0
    OpenCASCADE Community Edition: 6.9.1
    Curl: 7.61.0
    Compiler: GCC 8.2.0 with C++ ABI 1013

Build settings:
    USE_WX_GRAPHICS_CONTEXT=OFF
    USE_WX_OVERLAY=OFF
    KICAD_SCRIPTING=ON
    KICAD_SCRIPTING_MODULES=ON
    KICAD_SCRIPTING_PYTHON3=OFF
    KICAD_SCRIPTING_WXPYTHON=OFF
    KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
    KICAD_SCRIPTING_ACTION_MENU=ON
    BUILD_GITHUB_PLUGIN=ON
    KICAD_USE_OCE=ON
    KICAD_USE_OCC=OFF
    KICAD_SPICE=ON



GDB where output:
#0  0x00007ffff64166d9 in __GI___poll (fds=0x5555557b2f40, nfds=4,
timeout=10)
    at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007ffff5c70e46 in  () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007ffff5c711d2 in g_main_loop_run ()
    at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007ffff5fef3e7 in gtk_main ()
    at /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
#4  0x00007ffff706cb05 in wxGUIEventLoop::DoRun() ()
    at /usr/lib/x86_64-linux-gnu/libwx_gtk2u_core-3.0.so.0
#5  0x00007ffff67dba93 in wxEventLoopBase::Run() ()
    at /usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#6  0x00007ffff70d8cf3 in wxDialog::ShowModal() ()
    at /usr/lib/x86_64-linux-gnu/libwx_gtk2u_core-3.0.so.0
#7  0x00007fffde298bd8 in  () at /usr/lib/kicad-
nightly/bin/_eeschema.kiface
#8  0x00007fffde3d20ba in  () at /usr/lib/kicad-
nightly/bin/_eeschema.kiface
#9  0x00007fffde3d4a35 in  () at /usr/lib/kicad-
nightly/bin/_eeschema.kiface
#10 0x00007fffde2b3dee in  () at /usr/lib/kicad-
nightly/bin/_eeschema.kiface
#11 0x00007ffff691f4be in
wxEvtHandler::ProcessEventIfMatchesId(wxEventTableEntryBase const&,
wxEvtHandler*, wxEvent&) ()
    at /usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#12 0x00007ffff691f8ca in wxEvtHandler::SearchDynamicEventTable(wxEvent&)
()
    at /usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#13 0x00007ffff691f95f in wxEvtHandler::TryHereOnly(wxEvent&) ()
--Type <RET> for more, q to quit, c to continue without paging--RET
    at /usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#14 0x00007ffff691fa13 in wxEvtHandler::ProcessEventLocally(wxEvent&) ()
    at /usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#15 0x00007ffff691fa75 in wxEvtHandler::ProcessEvent(wxEvent&) ()
    at /usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#16 0x00007ffff691f7d7 in wxEvtHandler::SafelyProcessEvent(wxEvent&) ()
    at /usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#17 0x00007ffff70cd4b7 in  ()
    at /usr/lib/x86_64-linux-gnu/libwx_gtk2u_core-3.0.so.0
#18 0x00007ffff5dc1b6d in g_closure_invoke ()
    at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#19 0x00007ffff5dd43ee in  () at /usr/lib/x86_64-linux-
gnu/libgobject-2.0.so.0
#20 0x00007ffff5ddd882 in g_signal_emit_valist ()
    at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#21 0x00007ffff5dddecf in g_signal_emit ()
    at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#22 0x00007ffff5f4bfb5 in  () at /usr/lib/x86_64-linux-
gnu/libgtk-x11-2.0.so.0
#23 0x00007ffff5dc1b6d in g_closure_invoke ()
    at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#24 0x00007ffff5dd4a96 in  () at /usr/lib/x86_64-linux-
gnu/libgobject-2.0.so.0
#25 0x00007ffff5ddd882 in g_signal_emit_valist ()
    at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#26 0x00007ffff5dddecf in g_signal_emit ()
--Type <RET> for more, q to quit, c to continue without paging--RET
    at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#27 0x00007ffff5f4aef9 in  () at /usr/lib/x86_64-linux-
gnu/libgtk-x11-2.0.so.0
#28 0x00007ffff5ff1cfb in  () at /usr/lib/x86_64-linux-
gnu/libgtk-x11-2.0.so.0
#29 0x00007ffff5dc1b6d in g_closure_invoke ()
    at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#30 0x00007ffff5dd4124 in  () at /usr/lib/x86_64-linux-
gnu/libgobject-2.0.so.0
#31 0x00007ffff5ddcf43 in g_signal_emit_valist ()
    at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#32 0x00007ffff5dddecf in g_signal_emit ()
    at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#33 0x00007ffff610900c in  () at /usr/lib/x86_64-linux-
gnu/libgtk-x11-2.0.so.0
#34 0x00007ffff5feff9c in gtk_propagate_event ()
    at /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
#35 0x00007ffff5ff038b in gtk_main_do_event ()
    at /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
#36 0x00007ffff5e60ccc in  () at /usr/lib/x86_64-linux-
gnu/libgdk-x11-2.0.so.0
#37 0x00007ffff5c70c3e in g_main_context_dispatch ()
    at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#38 0x00007ffff5c70ed8 in  () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#39 0x00007ffff5c711d2 in g_main_loop_run ()
    at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#40 0x00007ffff5fef3e7 in gtk_main ()
    at /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
--Type <RET> for more, q to quit, c to continue without paging--RET
#41 0x00007ffff706cb05 in wxGUIEventLoop::DoRun() ()
    at /usr/lib/x86_64-linux-gnu/libwx_gtk2u_core-3.0.so.0
#42 0x00007ffff67dba93 in wxEventLoopBase::Run() ()
    at /usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#43 0x00007fffde567fc7 in  () at /usr/lib/kicad-
nightly/bin/_eeschema.kiface
#44 0x00007fffde373867 in  () at /usr/lib/kicad-
nightly/bin/_eeschema.kiface
#45 0x00005555555f2610 in  ()
#46 0x00005555555f2836 in  ()
#47 0x00007ffff691f4be in
wxEvtHandler::ProcessEventIfMatchesId(wxEventTableEntryBase const&,
wxEvtHandler*, wxEvent&) ()
    at /usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#48 0x00007ffff691f5c3 in wxEventHashTable::HandleEvent(wxEvent&,
wxEvtHandler*) () at /usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#49 0x00007ffff691f98b in wxEvtHandler::TryHereOnly(wxEvent&) ()
    at /usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#50 0x00007ffff691fa13 in wxEvtHandler::ProcessEventLocally(wxEvent&) ()
    at /usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#51 0x00007ffff691fa75 in wxEvtHandler::ProcessEvent(wxEvent&) ()
    at /usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#52 0x000055555563632c in  ()
#53 0x00007ffff6920be2 in wxEvtHandler::ProcessPendingEvents() ()
    at /usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#54 0x00007ffff67a19e7 in wxAppConsoleBase::ProcessPendingEvents() ()
--Type <RET> for more, q to quit, c to continue without paging--c
    at /usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#55 0x00007ffff704cbbd in wxApp::DoIdle() () at /usr/lib/x86_64-linux-
gnu/libwx_gtk2u_core-3.0.so.0
#56 0x00007ffff704ccc3 in  () at /usr/lib/x86_64-linux-
gnu/libwx_gtk2u_core-3.0.so.0
#57 0x00007ffff5c70ae8 in g_main_context_dispatch () at
/usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#58 0x00007ffff5c70ed8 in  () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#59 0x00007ffff5c711d2 in g_main_loop_run () at /usr/lib/x86_64-linux-
gnu/libglib-2.0.so.0
#60 0x00007ffff5fef3e7 in gtk_main () at /usr/lib/x86_64-linux-
gnu/libgtk-x11-2.0.so.0
#61 0x00007ffff706cb05 in wxGUIEventLoop::DoRun() () at
/usr/lib/x86_64-linux-gnu/libwx_gtk2u_core-3.0.so.0
#62 0x00007ffff67dba93 in wxEventLoopBase::Run() () at
/usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#63 0x00007ffff67a30a6 in wxAppConsoleBase::MainLoop() () at
/usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#64 0x00005555555f09b9 in  ()
#65 0x00007ffff682dae9 in wxEntry(int&, wchar_t**) () at
/usr/lib/x86_64-linux-gnu/libwx_baseu-3.0.so.0
#66 0x00005555555d68b8 in  ()
#67 0x00007ffff632c09b in __libc_start_main (main=0x5555555d6890, argc=1,
argv=0x7fffffffdd98, init=<optimized out>, fini=<optimized out>,
rtld_fini=<optimized out>, stack_end=0x7fffffffdd88) at ../csu/libc-
start.c:308
```

Story points: 6.0