histedit: convert pick action into a class

This converts the pick action into a histeditclass instance, as part of an
ongoing effort to refactor histedit for maintainability and robustness.

The test output changed because previously pick would only report the commit
disappearing if there were no merge conflicts. Now that we've unified the normal
and the --continue flows, they act the same and we get the warning even after
--continue.

hgext/histedit.py

@@ -487,28 +487,14 def collapse(repo, first, last, commitop
                          editor=editor)
     return repo.commitctx(new)
 
-def pick(ui, state, ha, opts):
-    repo, ctxnode = state.repo, state.parentctxnode
-    ctx = repo[ctxnode]
-    oldctx = repo[ha]
-    if oldctx.parents()[0] == ctx:
-        ui.debug('node %s unchanged\n' % ha[:12])
-        return oldctx, []
-    hg.update(repo, ctx.node())
-    stats = applychanges(ui, repo, oldctx, opts)
-    if stats and stats[3] > 0:
-        raise error.InterventionRequired(_('Fix up the change and run '
-                                           'hg histedit --continue'))
-    # drop the second merge parent
-    commit = commitfuncfor(repo, oldctx)
-    n = commit(text=oldctx.description(), user=oldctx.user(),
-               date=oldctx.date(), extra=oldctx.extra())
-    if n is None:
-        ui.warn(_('%s: empty changeset\n') % ha[:12])
-        return ctx, []
-    new = repo[n]
-    return new, [(oldctx.node(), (n,))]
+class pick(histeditaction):
+    def run(self):
+        rulectx = self.repo[self.node]
+        if rulectx.parents()[0].node() == self.state.parentctxnode:
+            self.repo.ui.debug('node %s unchanged\n' % node.short(self.node))
+            return rulectx, []
 
+        return super(pick, self).run()
 
 def edit(ui, state, ha, opts):
     repo, ctxnode = state.repo, state.parentctxnode
@@ -939,7 +925,7 def bootstrapcontinue(ui, state, opts):
             else:
                 message = ctx.description()
             editopt = action in ('e', 'edit', 'm', 'mess')
-            canonaction = {'e': 'edit', 'm': 'mess', 'p': 'pick'}
+            canonaction = {'e': 'edit', 'm': 'mess'}
             editform = 'histedit.%s' % canonaction.get(action, action)
             editor = cmdutil.getcommiteditor(edit=editopt, editform=editform)
             commit = commitfuncfor(repo, ctx)

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

@@ -132,6 +132,7 just continue this time
   $ hg resolve --mark e
   (no more unresolved files)
   $ hg histedit --continue 2>&1 | fixbundle
+  7b4e2f4b7bcd: empty changeset
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
@@ -274,6 +275,7 just continue this time
   $ hg resolve --mark e
   (no more unresolved files)
   $ hg histedit --continue 2>&1 | fixbundle
+  7b4e2f4b7bcd: empty changeset
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
 

tests/test-histedit-non-commute.t

@@ -170,6 +170,7 just continue this time
   $ hg resolve --mark e
   (no more unresolved files)
   $ hg histedit --continue 2>&1 | fixbundle
+  7b4e2f4b7bcd: empty changeset
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
@@ -253,6 +254,7 second edit also fails, but just continu
   $ hg resolve --mark e
   (no more unresolved files)
   $ hg histedit --continue 2>&1 | fixbundle
+  7b4e2f4b7bcd: empty changeset
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved