pull-request lock is ignored in edge cases

[WULCAN]

On e5d3297, the route for creating a pull request implements a lock to reduce the risk of concurrent calls interfering with each other.

We have another integration with the local git clone in Cache.gitPullIfNeeded and this does not respect the lock so some risk remains.

gitPullIfNeeded does no work on the local git clone if the project has already been loaded into Lyra and normally, the language will have been loaded before creating any pull request.

The risk of any interference during normal use is very low.