Using Bazaar
Bazaar is a free version control system sponsored by Canonical.
In addition to the standard version control system functions described in Using Common Functions, you can select Tools > Bazaar > Pull to turn a branch into a mirror of another branch. To update the mirror of the branch, select Push.
Uncommitting Revisions
In Bazaar, committing changes to a branch creates a new revision that holds a snapshot of the state of the working tree. To remove the last committed revision, select Tools > Bazaar > Uncommit.
In the Uncommit dialog, select options to keep tags that point to removed revisions and to only remove the commits from the local branch when in a checkout.
To remove all commits up to an entry in the revision log, specify the revision in the Revision field.
To test the outcome of the Uncommit command without actually removing anything, select Dry Run.
Uncommit leaves the working tree ready for a new commit. The only change it might make is restoring pending merges that were present before the commit.