Issue #19936: Disable shebang lines in order to prevent using a random
system python.
update pysqlite website (closes #20278)
linkify chain.from_iterable (closes #20272)
Issue #19936: Added executable bits or shebang lines to Python scripts which
requires them.  Disable executable bits and shebang lines in test and
benchmark files in order to prevent using a random system python, and in
source files of modules which don't provide command line interface.  Fixed
shebang line to use python3 executable in the unittestgui script.
Merge heads
Issue #19936: Remove executable bits from C source files and several forgotten
test files.