diff --git a/hgext3rd/conflictinfo.py b/hgext3rd/conflictinfo.py
--- a/hgext3rd/conflictinfo.py
+++ b/hgext3rd/conflictinfo.py
@@ -55,15 +55,17 @@
     ['rebasestate', {'cmd': 'rebase',
                      'to_continue': 'rebase --continue',
                      'to_abort': 'rebase --abort'}],
-    ['merge/state', {'cmd': 'merge',
-                    'to_continue': 'merge --continue',
-                    'to_abort': 'update --clean'}],
     ['shelvedstate', {'cmd': 'unshelve',
                       'to_continue': 'unshelve --continue',
                       'to_abort': 'unshelve --abort'}],
     ['histedit-state', {'cmd': 'histedit',
                         'to_continue': 'histedit --continue',
                         'to_abort': 'histedit --abort'}],
+    # merge should be last, because some of the above leave their own state and
+    # a merge state in some pathological cases, and need to be aborted first.
+    ['merge/state', {'cmd': 'merge',
+                     'to_continue': 'merge --continue',
+                     'to_abort': 'update --clean'}],
 ]
 
 def extsetup(ui):
@@ -72,7 +74,7 @@
 # Returns which command got us into the conflicted merge state. Since these
 # states are mutually exclusive, we can use the existence of any one statefile
 # as proof of culpability.
-def _findconflictcommand(repo):
+def findconflictcommand(repo):
     for path, data in CONFLICTSTATES:
         if repo.vfs.exists(path):
             return data
@@ -114,7 +116,7 @@
             if info is not None:
                 pathconflicts.append(info)
 
-        cmd = _findconflictcommand(repo)
+        cmd = findconflictcommand(repo)
         formatter.startitem()
         formatter.write('conflicts', '%s\n', fileconflicts)
         formatter.write('pathconflicts', '%s\n', pathconflicts)
diff --git a/hgext3rd/continue.py b/hgext3rd/continue.py
new file mode 100644
--- /dev/null
+++ b/hgext3rd/continue.py
@@ -0,0 +1,48 @@
+#
+# Copyright 2017 Facebook, Inc.
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+
+"""continues an interrupted command (figures out what command you interupted)
+"""
+
+from mercurial import (
+    cmdutil,
+    dispatch,
+    error,
+    extensions,
+    registrar
+)
+
+from mercurial.i18n import _
+
+from hgext3rd.conflictinfo import findconflictcommand
+
+cmdtable = {}
+command = registrar.command(cmdtable)
+testedwith = 'ships-with-fb-hgext'
+
+def _rerun(ui, repo, cmd):
+    req = dispatch.request(cmd, ui=ui, repo=repo)
+    dispatch.dispatch(req)
+
+@command('continue', [], _('hg continue'))
+def continuecmd(ui, repo, *revs, **opts):
+    """continues an interrupted command
+    """
+    cmd = findconflictcommand(repo)
+    if cmd is None:
+        raise error.Abort(_('nothing to continue'))
+
+    _rerun(ui, repo, cmd['to_continue'].split(' '))
+
+@command('abort', [], _('hg abort'))
+def abortcmd(ui, repo, *revs, **opts):
+    """aborts an interrupted command
+    """
+    cmd = findconflictcommand(repo)
+    if cmd is None:
+        raise error.Abort(_('nothing to abort'))
+
+    _rerun(ui, repo, cmd['to_abort'].split(' '))
diff --git a/hgext3rd/undo.py b/hgext3rd/undo.py
--- a/hgext3rd/undo.py
+++ b/hgext3rd/undo.py
@@ -124,7 +124,8 @@
                 # upstream change.
                 repo.invalidatevolatilesets()
                 safelog(repo, command)
-                del os.environ['_undologactive']
+                if '_undologactive' in os.environ:
+                    del os.environ['_undologactive']
 
     return result