False positive on rejecting a push with multiple branches

Added a fix at 2 branches, and pushed them both. They both failed.

$ git push project 308-add-cif2cif-eventcontr-transformations 320-remove-unused-alg-variables
...
 ! [remote rejected]   308-add-cif2cif-eventcontr-transformations -> 308-add-cif2cif-eventcontr-transformations (pre-receive hook declined)
 ! [remote rejected]   320-remove-unused-alg-variables -> 320-remove-unused-alg-variables (pre-receive hook declined)
error: failed to push some refs to 'git@gitlab.eclipse.org:eclipse/escet/escet.git'

Checking #308 (closed), finding it fine, and pushing it works

$ git lg 308-add-cif2cif-eventcontr-transformations
* 2559cd70 (HEAD -> 308-add-cif2cif-eventcontr-transformations) #308 More fixes
...

$ git push project 308-add-cif2cif-eventcontr-transformations
...
# Ok!

$ git lg 320-remove-unused-alg-variables
* 8377fd93 (HEAD -> 320-remove-unused-alg-variables) Add copyright line.
...

This one was wrong indeed.