[web] fix os.rename usage on windows when destination exists
os.rename on windows will raise OSError (or WindowsError subclass) when if
destination file already exists.
Also check that exception is EEXIST.
There is an attempt to fix in f6ba947c but using IOError instead of OSError.
Closes #14214794
include *.py
include */*.py
recursive-include data *.gif *.png *.ico *.css *.js
recursive-include i18n *.po
recursive-include wdoc *