histedit: don't clobber working copy on --abort if not on histedit cset

Similar to issue4009, 2.7 will force people to abort histedits before
doing interesting things. Without this fix, people with histedit
sessions they wandered away from before upgrading to 2.7 could clobber
their working copy for no reason.

hgext/histedit.py

@@ -506,7 +506,14 b' def histedit(ui, repo, *freeargs, **opts'
         (parentctxnode, rules, keep, topmost, replacements) = readstate(repo)
         mapping, tmpnodes, leafs, _ntm = processreplacement(repo, replacements)
         ui.debug('restore wc to old parent %s\n' % node.short(topmost))
-        hg.clean(repo, topmost)
+        # check whether we should update away
+        parentnodes = [c.node() for c in repo[None].parents()]
+        for n in leafs | set([parentctxnode]):
+            if n in parentnodes:
+                hg.clean(repo, topmost)
+                break
+        else:
+            pass
         cleanupnode(ui, repo, 'created', tmpnodes)
         cleanupnode(ui, repo, 'temp', leafs)
         os.unlink(os.path.join(repo.path, 'histedit-state'))

tests/test-histedit-no-change.t

@@ -169,13 +169,34 b' check state of working copy'
   o  0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a"
   
 
-abort editing session
+abort editing session, after first forcibly updating away
+  $ hg up 0
+  abort: histedit in progress
+  (use 'hg histedit --continue' or 'hg histedit --abort')
+  [255]
+  $ mv .hg/histedit-state .hg/histedit-state-ignore
+  $ hg up 0
+  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
+  $ mv .hg/histedit-state-ignore .hg/histedit-state
+  $ hg sum
+  parent: 0:cb9a9f314b8b 
+   a
+  branch: default
+  commit: 1 modified, 1 unknown (new branch head)
+  update: 6 new changesets (update)
+  hist:   2 remaining (histedit --continue)
+
   $ hg histedit --abort 2>&1 | fixbundle
-  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  [1]
+
+modified files should survive the abort when we've moved away already
+  $ hg st
+  M e
+  ? edit.sh
 
   $ graphlog "log after abort"
   % log after abort
-  @  5 652413bf663ef2a641cab26574e46d5f5a64a55a "f"
+  o  5 652413bf663ef2a641cab26574e46d5f5a64a55a "f"
   |
   o  4 e860deea161a2f77de56603b340ebbb4536308ae "e"
   |
@@ -185,7 +206,7 b' abort editing session'
   |
   o  1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b"
   |
-  o  0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a"
+  @  0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a"
   
 
   $ cd ..