Fix target platform conflict between users

Using Studio with BM:

• Instance is registered with user solen
• Project is StudioProject

• User Bertrand switches to advanced commit mode
• User Solen is in simple mode

• User Bertrand defines target platform 5.8 for the project and saves
• User Solen defines target platform 5.6 for the project and saves
• User Bertrand commits but does not push yet

=> User Bertrand has 1 commit to push, 1 commit to pull
=> He cannot do either of them, and gets an error 500 each time