git-codereview: don't exit when remote.origin.pushurl isn't set
git-codereview: don't exit when remote.origin.pushurl isn't set

Change-Id: Id53f54f5a248317b149da6d2bec851db7dcf4913
Signed-off-by: Minux <72d850dbd8858b791995463d8539b5a379577f28@golang.org>
Reviewed-on: https://go.minux.info/8
Reviewed-by: Oling Cat <c230045f109dfb851e54f0b6c1a3f0e2626ca2fc@gmail.com>

Go-zh/review