Add command qheader to display the header of a given patch.

hgext/mq.py

@@ -1289,6 +1289,21 b' def diff(ui, repo, *files, **opts):'
     repo.mq.diff(repo, list(files))
     return 0
 
+def header(ui, repo, patch=None):
+    """Print the header of the topmost or specified patch"""
+    q = repo.mq
+
+    if patch:
+        patch = q.lookup(patch)
+    else:
+        if not q.applied:
+            ui.write('No patches applied\n')
+            return
+        patch = q.lookup('qtip')
+    message = repo.mq.readheaders(patch)[0]
+
+    ui.write('\n'.join(message) + '\n')
+
 def lastsavename(path):
     (dir, base) = os.path.split(path)
     names = os.listdir(dir)
@@ -1447,6 +1462,8 b' cmdtable = {'
          'hg qcommit [OPTION]... [FILE]...'),
     "^qdiff": (diff, [], 'hg qdiff [FILE]...'),
     "qdelete": (delete, [], 'hg qdelete PATCH'),
+    'qheader': (header, [],
+                _('hg qheader [PATCH]')),
     "^qimport":
         (qimport,
          [('e', 'existing', None, 'import file in patch dir'),

tests/test-mq.out

@@ -29,6 +29,7 b' list of commands (use "hg help -v mq" to'
  qcommit      commit changes in the queue repository
  qdelete      remove a patch from the series file
  qdiff        diff of the current patch
+ qheader      Print the header of the topmost or specified patch
  qimport      import a patch
  qinit        init a new queue repository
  qnew         create a new patch