Nightly PCBNEW crash at open (lp:#1851703)

[Original report](https://bugs.launchpad.net/bugs/1851703) created by **Michele Giorato (mr-miky64)**
```

In the last two versions nightly, opening a project and starting pcbnew you
get a kicad crash.

------------------------------------------------------------

michele@fx-8350-fc30 ~]$ kicad
19:47:33: Debug: Adding duplicate image handler for 'PNG file'
19:47:33: Debug: Adding duplicate image handler for 'JPEG file'
19:47:33: Debug: Adding duplicate image handler for 'TIFF file'
19:47:33: Debug: Adding duplicate image handler for 'GIF file'
19:47:33: Debug: Adding duplicate image handler for 'PNM file'
19:47:33: Debug: Adding duplicate image handler for 'PCX file'
19:47:33: Debug: Adding duplicate image handler for 'IFF file'
19:47:33: Debug: Adding duplicate image handler for 'Windows icon file'
19:47:33: Debug: Adding duplicate image handler for 'Windows cursor file'
19:47:33: Debug: Adding duplicate image handler for 'Windows animated
cursor file'
19:47:33: Debug: Adding duplicate image handler for 'TGA file'
19:47:33: Debug: Adding duplicate image handler for 'XPM file'
19:47:34: Debug: Loading project
'/home/michele/Documenti/pcb/kicad/MqttControl/MqttControl/MqttControl.pro'
settings.
kicad:
/builddir/build/BUILD/kicad-r17042-a60fb9a4/pcbnew/connectivity/connectivity_items.cpp:116:
virtual const VECTOR2I CN_ITEM::GetAnchor(int) const: Assertion `false'
failed.
kicad:
/builddir/build/BUILD/kicad-r17042-a60fb9a4/pcbnew/connectivity/connectivity_items.cpp:116:
virtual const VECTOR2I CN_ITEM::GetAnchor(int) const: Assertion `false'
failed.
Aborted (core dumped)


Application: KiCad
Version: 5.99.0-unknown-r17042-a60fb9a4, debug build
Libraries:
    wxWidgets 3.0.4
    libcurl/7.65.3 OpenSSL/1.1.1d-fips zlib/1.2.11 brotli/1.0.7
libidn2/2.2.0 libpsl/0.20.2 (+libidn2/2.0.5) libssh/0.9.0/openssl/zlib
nghttp2/1.39.2
Platform: Linux 5.3.8-200.fc30.x86_64 x86_64, 64 bit, Little endian, wxGTK
Build Info:
    Build date: Nov  6 2019 23:57:05
    wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
    Boost: 1.69.0
    OpenCASCADE Community Edition: 6.9.1
    Curl: 7.65.3
    Compiler: GCC 9.2.1 with C++ ABI 1013

Build settings:
    KICAD_SCRIPTING=ON
    KICAD_SCRIPTING_MODULES=ON
    KICAD_SCRIPTING_PYTHON3=ON
    KICAD_SCRIPTING_WXPYTHON=ON
    KICAD_SCRIPTING_WXPYTHON_PHOENIX=ON
    KICAD_SCRIPTING_ACTION_MENU=ON
    BUILD_GITHUB_PLUGIN=ON
    KICAD_USE_OCE=ON
    KICAD_USE_OCC=OFF
    KICAD_SPICE=ON
    KICAD_STDLIB_DEBUG=OFF
    KICAD_STDLIB_LIGHT_DEBUG=OFF
    KICAD_SANITIZE=OFF

------------------------------------------------------



If I downgrade to kicad-100:r17012-9bccbaf4.fc30.x86_64 version everything
works correctly.



Application: KiCad
Version: 5.99.0-unknown-r17012-9bccbaf4, debug build
Libraries:
    wxWidgets 3.0.4
    libcurl/7.65.3 OpenSSL/1.1.1d-fips zlib/1.2.11 brotli/1.0.7
libidn2/2.2.0 libpsl/0.20.2 (+libidn2/2.0.5) libssh/0.9.0/openssl/zlib
nghttp2/1.39.2
Platform: Linux 5.3.8-200.fc30.x86_64 x86_64, 64 bit, Little endian, wxGTK
Build Info:
    Build date: Nov  2 2019 02:00:48
    wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
    Boost: 1.69.0
    OpenCASCADE Community Edition: 6.9.1
    Curl: 7.65.3
    Compiler: GCC 9.2.1 with C++ ABI 1013

Build settings:
    KICAD_SCRIPTING=ON
    KICAD_SCRIPTING_MODULES=ON
    KICAD_SCRIPTING_PYTHON3=ON
    KICAD_SCRIPTING_WXPYTHON=ON
    KICAD_SCRIPTING_WXPYTHON_PHOENIX=ON
    KICAD_SCRIPTING_ACTION_MENU=ON
    BUILD_GITHUB_PLUGIN=ON
    KICAD_USE_OCE=ON
    KICAD_USE_OCC=OFF
    KICAD_SPICE=ON
    KICAD_STDLIB_DEBUG=OFF
    KICAD_STDLIB_LIGHT_DEBUG=OFF
    KICAD_SANITIZE=OFF
```
Original tags: pcbnew

Story points: 6.0