File system change monitoring not working under windows when executing bin/git-cola.exe

[ThiemoVanEngelen]

This is caused by a problem in pynsist (see pynsist issue 199 ), which sets bin/ as installdir in the preamble, and because of that adds bin/pkgs/ to the site dir and the sys.paths.

This could be solved in the extra-preamble script, specifically for commands.