R1:ffe654e5e30e

Fix directory moves and copies in Subversion hosted repositories

Summary: Fixes T6490.

Test Plan:
```
$ svn mv dir/ dir2
A dir2
D dir
D dir/list.txt

$ svn commit -m 'Move dir/ to dir2/'
Deleting dir
Adding dir2

Committed revision 3.

$ svn cp dir2/ dir3
A dir3

$ svn commit -m 'Copy dir2/ to dir3/'
Adding dir3

Committed revision 4.
```

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T6490

Differential Revision…