bug 1056380 - avoid double-attach
Revert "bug 983322 - sanitize preferencesBranch"
Merge pull request #1661 from zombie/1056380-double-attach

bug 1056380 - prevent double-attach, r=@jsantell
Merge pull request #1665 from mozilla/revert-1648-983322-sane-prefsBranch

Revert "bug 983322 - sanitize preferencesBranch"