merge default into stable for 2.2 code freeze

commit: add option to amend the working dir parent The --amend flag can be used to amend the parent of the working directory with a new commit that contains the changes in the parent in addition to those currently reported by "hg status", if there are any. The old commit is stored in a backup bundle in ".hg/strip-backup"(see "hg help bundle" and "hg help unbundle" on how to restore it). Message, user and date are taken from the amended commit unless specified. When a message isn't specified on the command line, the editor will open with the message of the amended commit. It is not possible to amend public changesets (see "hg help phases") or changesets that have children. Behind the scenes, first commit the update (if there is one) as a regular child of the current parent. Then create a new commit on the parent's parent with the updated contents. Then change the working copy parent to this new combined changeset. Finally, strip the amended commit and update commit created in the beginning. An alternative (cleaner?) approach of doing this is suggested here: http://selenic.com/pipermail/mercurial-devel/2012-March/038540.html It is currently not possible to amend merge commits or recursively, this can be added at a later time.