Add additional validation when creating merge requests

[zaquestion]

I've run into 2 cases where lab permitted creating an MR when it really shouldn't have.

• source branch was not present on source remote (creates an MR with an unavailable branch)
• source branch is already up to day with target
  • observed when forgetting to commit changes and starting an MR

[bmess]

I observed the first bullet point this evening. I don't think it's the fault of the tool, but perhaps it would provide expected behavior of it checked for the source branch to exist.

I think automatically pushing the branch could be dangerous, but maybe if it's not force pushed? I'm not sure.

Just a warning from the MR creation that source branch doesn't exist & and exit might be enough. Maybe include a flag to automatically push the branch if it doesn't exist, as long as it's up to the user to do the override from the less dangerous behavior of a push without alerting.

edit:

git version 2.13.6
lab version 0.3.1

[zaquestion]

Tempted to change the defaults when I fix this as well. Currently lab assumes origin/upstream if the branch doesn't point to its remote. Perhaps the forked remote should be the default which would likely reduce the chances of hitting this case entirely.

[zaquestion]

Bullet point 1 fixed in 0.5.2

[bmeneg]

Bullet point 2 fixed in 0.22.0 by 4f8cc17.