new: repo init --local-only
t/repo-push-subcommand

New repo push subcommand, which push to Git server directly,
not through the Gerrit Server.

Signed-off-by: Jiang Xin <jiangxin@ossxp.com>
opt: remove python warning
opt: compat python3
Fix a bug in repo push --cbr

repo push --cbr bailed out if some branches did not have
modifications when it is used.

Change-Id: I35f264ff7d77bb4bf8f26b4c3faffa184920b6c5
log: add print() when continue
opt: repo branch -- show '='
new: REPO_PRINT
new: REPO_PRINT about repo start
new: repo start --track-upstream
new: REPO_PRINT in git_config.py