pwcli: GitError must have a valid log
pwcli: GitError must have a valid log

Otherwise printing it out yields str + None, which fails
and hides the real error.

Signed-off-by: Johannes Berg <8398eb9892c5ab2ff439ca0b5e4b0706dd9ebef9@sipsolutions.net>

kvalo/pwcli,kvalo/pwcli