--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -1476,15 +1476,21 @@ def import_(ui, repo, patch1, *patches, 
     text/plain body parts before first diff are added to commit
     message.
 
-    If imported patch was generated by hg export, user and description
+    If the imported patch was generated by hg export, user and description
     from patch override values from message headers and body.  Values
     given on command line with -m and -u override these.
 
+    If --exact is specified, import will set the working directory
+    to the parent of each patch before applying it, and will abort
+    if the resulting changeset has a different ID than the one
+    recorded in the patch. This may happen due to character set
+    problems or other deficiencies in the text patch format.
+
     To read a patch from standard input, use patch name "-".
     """
     patches = (patch1,) + patches
 
-    if not opts['force']:
+    if opts.get('exact') or not opts['force']:
         bail_if_changed(repo)
 
     d = opts["base"]
@@ -1498,10 +1504,10 @@ def import_(ui, repo, patch1, *patches, 
 
         if pf == '-':
             ui.status(_("applying patch from stdin\n"))
-            tmpname, message, user, date = patch.extract(ui, sys.stdin)
+            tmpname, message, user, date, nodeid, p1, p2 = patch.extract(ui, sys.stdin)
         else:
             ui.status(_("applying %s\n") % p)
-            tmpname, message, user, date = patch.extract(ui, file(pf))
+            tmpname, message, user, date, nodeid, p1, p2 = patch.extract(ui, file(pf))
 
         if tmpname is None:
             raise util.Abort(_('no diffs found'))
@@ -1519,13 +1525,36 @@ def import_(ui, repo, patch1, *patches, 
                 message = None
             ui.debug(_('message:\n%s\n') % message)
 
+            wp = repo.workingctx().parents()
+            if opts.get('exact'):
+                if not nodeid or not p1:
+                    raise util.Abort(_('not a mercurial patch'))
+                p1 = repo.lookup(p1)
+                p2 = repo.lookup(p2 or hex(nullid))
+
+                if p1 != wp[0].node():
+                    hg.clean(repo, p1, wlock=wlock)
+                repo.dirstate.setparents(p1, p2)
+            elif p2:
+                try:
+                    p1 = repo.lookup(p1)
+                    p2 = repo.lookup(p2)
+                    if p1 == wp[0].node():
+                        repo.dirstate.setparents(p1, p2)
+                except RepoError:
+                    pass
+
             files = {}
             try:
                 fuzz = patch.patch(tmpname, ui, strip=strip, cwd=repo.root,
                                    files=files)
             finally:
                 files = patch.updatedir(ui, repo, files, wlock=wlock)
-            repo.commit(files, message, user, date, wlock=wlock, lock=lock)
+            n = repo.commit(files, message, user, date, wlock=wlock, lock=lock)
+            if opts.get('exact'):
+                if hex(n) != nodeid:
+                    repo.rollback()
+                    raise util.Abort(_('patch is damaged or loses information'))
         finally:
             os.unlink(tmpname)
 
@@ -2771,7 +2800,9 @@ table = {
              'meaning as the corresponding patch option')),
           ('b', 'base', '', _('base path')),
           ('f', 'force', None,
-           _('skip check for outstanding uncommitted changes'))] + commitopts,
+           _('skip check for outstanding uncommitted changes')),
+          ('', 'exact', None,
+           _('apply patch to the nodes from which it was generated'))] + commitopts,
          _('hg import [-p NUM] [-m MESSAGE] [-f] PATCH...')),
     "incoming|in": (incoming,
          [('M', 'no-merges', None, _('do not show merges')),