histedit: attempt to make merge labels more helpful

Differential Revision: https://phab.mercurial-scm.org/D12023

hgext/histedit.py

@@ -667,7 +667,15 b' def applychanges(ui, repo, ctx, opts):'
             repo.ui.setconfig(
                 b'ui', b'forcemerge', opts.get(b'tool', b''), b'histedit'
             )
-            stats = mergemod.graft(repo, ctx, labels=[b'local', b'histedit'])
+            stats = mergemod.graft(
+                repo,
+                ctx,
+                labels=[
+                    b'already edited',
+                    b'current change',
+                    b'parent of current change',
+                ],
+            )
         finally:
             repo.ui.setconfig(b'ui', b'forcemerge', b'', b'histedit')
     return stats

tests/test-histedit-non-commute-abort.t

@@ -77,8 +77,8 b' edit the history'
 insert unsupported advisory merge record
   $ hg --config extensions.fakemergerecord=$TESTDIR/fakemergerecord.py fakemergerecord -x
   $ hg debugmergestate
-  local (local): 8f7551c7e4a2f2efe0bc8c741baf7f227d65d758
-  other (histedit): e860deea161a2f77de56603b340ebbb4536308ae
+  local (already edited): 8f7551c7e4a2f2efe0bc8c741baf7f227d65d758
+  other (current change): e860deea161a2f77de56603b340ebbb4536308ae
   file: e (state "u")
     local path: e (hash 58e6b3a414a1e090dfc6029add0f3555ccba127f, flags "")
     ancestor path: e (node 0000000000000000000000000000000000000000)