I am not sure whether this is a Git or IntelliJ problem we are facing. Assuming the following using Git integration in IntelliJ:
User A changes a text file and commits and pushes this change to branch branch1
User B changes the same text file but in a different line and commits to branch1
User B fetches the remote repository and merges the remote branch1 into the local branch1
Current Behavior: It merges wihout any conflicts (since different lines?)
Wanted Behavior: Conflict Resolution Window popups up and User must decide whether to apply all none conflicting changes.
Same question here on stackoverflow: http://stackoverflow.com/questions/24425809/how-to-force-conflict-resolution-window-in-intellij-if-same-file-was-edited-by-a