pwcli: improve error handling related to git commands
pwcli: improve error handling related to git commands

Raise GitError() if something goes wrong and try to collect some logs if something fails.

Signed-off-by: Kalle Valo <7081a7d99b8c74c0698a728df19e3915a995d7e1@codeaurora.org>

kvalo/pwcli,kvalo/pwcli