Why do you pronounce it like that, though? I pronounce it like "geesh" or "guish" or "guiche" (not sure how to write it phonetically). It is just the Catalan word for "chalk".
If we were to reserve every word that is also used as slang for sexual organs we'd be out a lot of words. Peach, purse, shaft, sheath, tool, pocket, etc, these are all slang as well, yet we still use these for their original meaning. It's all about context. I'd also say 'gash' is quite regional. I've only ever heard it used in the U.K.
Australia too. Quite vulgar but not especially common nor especially rare.
Not the name of the project (which is pronounced 'geeks') but the implementation of the shell and coreutils, as from the text in the article. This implementation is called 'Gash'.