Perforce: 'Automatically open files when editing' not working anymore

This is a regression since 2.2.

When editing a file that is under Perforce version control, and trying to save it, the file is no longer automatically opened but instead an error dialog pops up (even though the option 'Automatically open files when editing' is enabled). It is currently necessary to click "Make writable" before saving the file, which is annoying.