Merged r12447 for 2.4.2 release.

git-svn-id: http://svn.redmine.org/redmine/branches/2.4-stable@12448 e93f8b46-1217-0410-a6f0-8f06a7374b81
backport r12453 AbstractAdapter change to 2.4-stable (#15756)

git-svn-id: http://svn.redmine.org/redmine/branches/2.4-stable@12454 e93f8b46-1217-0410-a6f0-8f06a7374b81
Merged r12456 from trunk to 2.4-stable (#15756)

change requirement in bazaar lib as same with other scm libs.

git-svn-id: http://svn.redmine.org/redmine/branches/2.4-stable@12458 e93f8b46-1217-0410-a6f0-8f06a7374b81
Revert "workaround for missing constant of CommandFailed"

This reverts commit dcfbeb6592372509c162cb1b7699aa93301c6e45.