getstash.py: can now update from different repo
getstash.py: can now update from different repo

The getstash.py script will now install stash from a different repo if told by the selfupdate command.
This file is currently only uploaded for testing. I will comment this commit once the tests are finished.
cclauss/stash,ywangd/stash,ywangd/stash,cclauss/stash