review command should have namespace or prefix option

[Andreas Hasenack]

Sometimes people do a merge using a bug number with the merge start command. That causes the tags to be prefixed by something like this:
lpbionic1717343/logical/5.5.1-4ubuntu3

The review command should have an option to expect such a prefix, or else it will fail like this:
$ git ubuntu review --clone https://code.launchpad.net/~paelzer/ubuntu/+source/strongswan/+git/strongswan/+merge/334520 -v
12/12/2017 10:30:23 - INFO:git ubuntu lint result:
W: paelzer/old/debian not found
W: paelzer/old/ubuntu not found
W: paelzer/new/debian not found
W: paelzer/reconstruct/5.5.1-4ubuntu3 not found
W: paelzer/logical/5.5.1-4ubuntu3 not found

I believe the lint command itself will need this too. I wasn't sure if the --lint-namespace option is meant for that, because the command fails on that same branch due to bug #1735744