Merge conflict resolve doesn't work when I deleted files.

(actually using 1.6.3, but Jira doesn't know that version yet).

I have two branches.
My current branch deleted a bunch of files.
A remote branch (origin/develop) altered files after the branch point.

Merge in branch origin/develop.
There correctly are a number of files in the list of conflicts.

I select all files and select the "Resolve Conflict->resolve using mine" option from the context menu.

I get "Could not update one or more files, please check that no other application is locking your files."

I expected that sourcetree marked the files deleted and resolved.