0.13dev: Preserves permissions and ownerships of old attachments directory for new attachments directory if possible
0.13dev: Preserves permissions and ownerships of old attachments directory for new attachments directory if possible

Part of #10313.


git-svn-id: eda3d06fcef731589ace1b284159cead3416df9b@11040 af82e41b-90c4-0310-8c96-b1721e28e2e2

walty8/trac,walty8/trac,jun66j5/trac-ja,walty8/trac,walty8/trac,jun66j5/trac-ja,jun66j5/trac-ja,netjunki/trac-Pygit2,netjunki/trac-Pygit2,netjunki/trac-Pygit2,jun66j5/trac-ja