histedit: fix --continue when rules are finished stable

histedit: fix --continue when rules are finished

If histedit failed after all the rules were complete (for instance, if there was
an exception in the cleanup phase), you couldn't --continue because it was
unable to pop a rule. Let's just skip the rule execution phase of --continue if
there are no more rules.

--- a/hgext/histedit.py	Fri May 01 15:28:47 2015 -0700
+++ b/hgext/histedit.py	Fri May 01 15:45:07 2015 -0700
@@ -893,21 +893,22 @@
 
 def bootstrapcontinue(ui, state, opts):
     repo = state.repo
-    action, currentnode = state.rules.pop(0)
-
-    actobj = actiontable[action].fromrule(state, currentnode)
+    if state.rules:
+        action, currentnode = state.rules.pop(0)
 
-    s = repo.status()
-    if s.modified or s.added or s.removed or s.deleted:
-        actobj.continuedirty()
+        actobj = actiontable[action].fromrule(state, currentnode)
+
         s = repo.status()
         if s.modified or s.added or s.removed or s.deleted:
-            raise util.Abort(_("working copy still dirty"))
+            actobj.continuedirty()
+            s = repo.status()
+            if s.modified or s.added or s.removed or s.deleted:
+                raise util.Abort(_("working copy still dirty"))
 
-    parentctx, replacements = actobj.continueclean()
+        parentctx, replacements = actobj.continueclean()
 
-    state.parentctxnode = parentctx.node()
-    state.replacements.extend(replacements)
+        state.parentctxnode = parentctx.node()
+        state.replacements.extend(replacements)
 
     return state