branch: added more support for named branches

hg branch now has a -C (--clean) option, to reset the current (dirstate)
branch to the branch of the last commit (first parent).

mercurial/commands.py

@@ -373,10 +373,17 b' def branch(ui, repo, label=None, **opts)'
     Unless --force is specified, branch will not let you set a
     branch name that shadows an existing branch.
 
+    Use --clean to reset the working directory branch to that of the
+    parent of the working directory, negating a previous branch change.
+
     Use the command 'hg update' to switch to an existing branch.
     """
 
-    if label:
+    if opts.get('clean'):
+        label = repo[None].parents()[0].branch()
+        repo.dirstate.setbranch(label)
+        ui.status(_('reset working directory to branch %s\n') % label)
+    elif label:
         if not opts.get('force') and label in repo.branchtags():
             if label not in [p.branch() for p in repo.parents()]:
                 raise util.Abort(_('a branch of the same name already exists'
@@ -2987,8 +2994,9 b' table = {'
     "branch":
         (branch,
          [('f', 'force', None,
-           _('set branch name even if it shadows an existing branch'))],
-         _('hg branch [-f] [NAME]')),
+           _('set branch name even if it shadows an existing branch')),
+          ('C', 'clean', None, _('reset branch name to parent branch name'))],
+         _('hg branch [-fC] [NAME]')),
     "branches":
         (branches,
          [('a', 'active', False,

tests/test-branches

@@ -11,6 +11,11 b' hg add a'
 hg branch a
 hg commit -d '1 0' -u test -m "Adding a branch"
 
+hg branch q
+echo 'aa' >a
+hg branch -C
+hg commit -d '2 0' -u test -m "Adding to a branch"
+
 hg update -C 0
 echo 'b' >b
 hg add b

tests/test-branches.out

@@ -1,21 +1,34 b''
 marked working directory as branch a
+marked working directory as branch q
+reset working directory to branch a
 0 files updated, 0 files merged, 1 files removed, 0 files unresolved
 marked working directory as branch b
 created new head
-0 files updated, 0 files merged, 1 files removed, 0 files unresolved
-created new head
+1 files updated, 0 files merged, 2 files removed, 0 files unresolved
 marked working directory as branch c
 marked working directory as branch a branch name much longer than the default justification used by branches
-a branch name much longer than the default justification used by branches 6:b8cb5af34c4d
-b                              4:22df7444f7c1
-a                              1:dd6b440dd85a
-c                              5:5ca481e59b8c (inactive)
+a branch name much longer than the default justification used by branches 7:10ff5895aa57
+b                              4:aee39cd168d0
+c                              6:589736a22561 (inactive)
+a                              5:d8cbc61dbaa6 (inactive)
 default                        0:19709c5a4e75 (inactive)
 -------
-a branch name much longer than the default justification used by branches 6:b8cb5af34c4d
-b                              4:22df7444f7c1
-a                              1:dd6b440dd85a
+a branch name much longer than the default justification used by branches 7:10ff5895aa57
+b                              4:aee39cd168d0
 --- Branch a
+changeset:   5:d8cbc61dbaa6
+branch:      a
+parent:      2:881fe2b92ad0
+user:        test
+date:        Thu Jan 01 00:00:04 1970 +0000
+summary:     Adding b branch head 2
+
+changeset:   2:881fe2b92ad0
+branch:      a
+user:        test
+date:        Thu Jan 01 00:00:02 1970 +0000
+summary:     Adding to a branch
+
 changeset:   1:dd6b440dd85a
 branch:      a
 user:        test
@@ -23,20 +36,13 b' date: Thu Jan 01 00:00:01 1970 +0'
 summary:     Adding a branch
 
 ---- Branch b
-changeset:   4:22df7444f7c1
-branch:      b
-parent:      2:ac22033332d1
-user:        test
-date:        Thu Jan 01 00:00:04 1970 +0000
-summary:     Adding b branch head 2
-
-changeset:   3:aee39cd168d0
+changeset:   4:aee39cd168d0
 branch:      b
 user:        test
 date:        Thu Jan 01 00:00:03 1970 +0000
 summary:     Adding b branch head 1
 
-changeset:   2:ac22033332d1
+changeset:   3:ac22033332d1
 branch:      b
 parent:      0:19709c5a4e75
 user:        test