[windows] problem when package name is part of project name/path

[LarsEckart]

Murphy's law strikes again, if anything can go wrong, it will. Issue found by a participant in my coding dojo session.
On windows, if the path name contains a word from the package name, our stacktrace namer can get into trouble:

Guess a picture demonstrates the issue best:

causes a wild exception and stacktrace because the path we calculate doesn't exist.

[LarsEckart]

fixed in 15.1.2