fix(server.go): don't reply false if lock fails

[mboersma]

Summary of Changes

Removes an uneeded req.Reply call that confused builder output during a simultaneous git push operation. This change was suggested by @kmala. :metal:

Associated End To End Test PR(s)

We will work on capturing this behavior in an e2e test next, but it is not required to merge this. See also deis/workflow-e2e#230.

Testing Instructions

1. Create a Deis Cluster
2. Register an app
3. git push the app but hit Ctrl+C to interrupt git while it is pushing
4. Retry the git push operation repeatedly and observe the results

What you should see:

$ git push deis master
Counting objects: 96, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (74/74), done.
Writing objects: 100% (96/96), 20.84 KiB | 0 bytes/s, done.
Total 96 (delta 40), reused 45 (delta 17)
^CKilled by signal 2.

$ git push deis master
fatal: remote error: Another git push is ongoing
$ git push deis master
fatal: remote error: Another git push is ongoing
$ git push deis master
fatal: remote error: Another git push is ongoing
$ echo $?
128
$ git push deis master
fatal: remote error: Another git push is ongoing
$ git push deis master
fatal: remote error: Another git push is ongoing
$ git push deis master
Everything up-to-date
$ echo $?
0

What you should no longer see (refs #365):

$ git push deis master
Counting objects: 96, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (74/74), done.
Writing objects: 100% (96/96), 20.84 KiB | 0 bytes/s, done.
Total 96 (delta 40), reused 45 (delta 17)
Starting build... but first, coffee!
^CKilled by signal 2.

$ git push deis master
exec request failed on channel 0
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
$ git push deis master
exec request failed on channel 0
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
$ git push deis master
exec request failed on channel 0
fatal: remote error: Another git push is ongoing
$ git push deis master
exec request failed on channel 0
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

Pull Request Hygiene TODOs

Please make sure the below checklist is complete.

• [X] Your pull request is concise and to the point (make another PR for refactoring nearby code)
• [X] Your commits follow the commit style guidelines

[deis-bot]

@aledbf, @smothiki and @arschles are potential reviewers of this pull request based on my analysis of git blame information. Thanks @mboersma!