histedit: don't allow to strip nodes which are necessary to continue histedit

During histedit we don't want user to do any operation resulting in
stripping nodes needed to continue history editing. This patch
wraps the strip function to detect such situations.

hgext/histedit.py

@@ -158,6 +158,7 b' from mercurial import discovery'
 from mercurial import error
 from mercurial import copies
 from mercurial import context
+from mercurial import extensions
 from mercurial import hg
 from mercurial import node
 from mercurial import repair
@@ -674,6 +675,7 b' def _histedit(ui, repo, state, *freeargs'
         actfunc = actiontable[action]
         state.parentctx, replacement_ = actfunc(ui, state, ha, opts)
         state.replacements.extend(replacement_)
+    state.write()
 
     hg.update(repo, state.parentctx.node())
 
@@ -971,6 +973,23 b' def cleanupnode(ui, repo, name, nodes):'
     finally:
         release(lock)
 
+def stripwrapper(orig, ui, repo, nodelist, *args, **kwargs):
+    if isinstance(nodelist, str):
+        nodelist = [nodelist]
+    if os.path.exists(os.path.join(repo.path, 'histedit-state')):
+        state = histeditstate(repo)
+        state.read()
+        histedit_nodes = set([ctx for (action, ctx) in state.rules])
+        strip_nodes = set([repo[n].hex() for n in nodelist])
+        common_nodes = histedit_nodes & strip_nodes
+        if common_nodes:
+            raise util.Abort(_('unable to strip %s. Nodes are '
+                               'used by history edit in progress.')
+                             % ', '.join(common_nodes))
+    return orig(ui, repo, nodelist, *args, **kwargs)
+
+extensions.wrapfunction(repair, 'strip', stripwrapper)
+
 def summaryhook(ui, repo):
     if not os.path.exists(repo.join('histedit-state')):
         return

tests/test-histedit-edit.t

@@ -3,6 +3,7 b''
   $ cat >> $HGRCPATH <<EOF
   > [extensions]
   > histedit=
+  > strip=
   > EOF
 
   $ initrepo ()
@@ -72,6 +73,11 b' Go at a random point and try to continue'
   (use 'hg histedit --continue' or 'hg histedit --abort')
   [255]
 
+Try to delete necessary commit
+  $ hg strip -r 652413bf663e
+  abort: unable to strip 652413bf663ef2a641cab26574e46d5f5a64a55a. Nodes are used by history edit in progress.
+  [255]
+
 commit, then edit the revision
   $ hg ci -m 'wat'
   created new head