git: tolerate improper configuration of source for development

git: tolerate improper configuration of source for development

Often one wants to create a git repo and start doing some explorative
work without setting up the repository on the server.

Allow this by downgrading the error messages to very loud warnings. Will
still fail to build in release mode.

Due to design limitations, multiple warnings may appear, but this might
be considered a good thing by some.

Signed-off-by: Tobias Ulmer <tu@emlix.com>