--- a/hgext/record.py	Fri Jan 31 15:25:31 2014 -0200
+++ b/hgext/record.py	Sat Feb 01 14:53:52 2014 -0600
@@ -601,12 +601,8 @@
             # it is important to first chdir to repo root -- we'll call
             # a highlevel command with list of pathnames relative to
             # repo root
-            cwd = os.getcwd()
-            os.chdir(repo.root)
-            try:
-                commitfunc(ui, repo, *newfiles, **opts)
-            finally:
-                os.chdir(cwd)
+            newfiles = [repo.wjoin(nf) for nf in newfiles]
+            commitfunc(ui, repo, *newfiles, **opts)
 
             return 0
         finally:

--- a/mercurial/dirstate.py	Fri Jan 31 15:25:31 2014 -0200
+++ b/mercurial/dirstate.py	Sat Feb 01 14:53:52 2014 -0600
@@ -162,8 +162,12 @@
         else:
             return fallback
 
+    @propertycache
+    def _cwd(self):
+        return os.getcwd()
+
     def getcwd(self):
-        cwd = os.getcwd()
+        cwd = self._cwd
         if cwd == self._root:
             return ''
         # self._root ends with a path separator if self._root is '/' or 'C:\'

--- a/mercurial/help/config.txt	Fri Jan 31 15:25:31 2014 -0200
+++ b/mercurial/help/config.txt	Sat Feb 01 14:53:52 2014 -0600
@@ -946,13 +946,16 @@
     Default: draft
 
 ``checksubrepos``
+    Check the phase of the current revision of each subrepository. Allowed
+    values are "ignore", "follow" and "abort". For settings other than
+    "ignore", the phase of the current revision of each subrepository is
+    checked before committing the parent repository. If any of those phases is
+    greater than the phase of the parent repository (e.g. if a subrepo is in a
+    "secret" phase while the parent repo is in "draft" phase), the commit is
+    either aborted (if checksubrepos is set to "abort") or the higher phase is
+    used for the parent repository commit (if set to "follow").
+    Default: "follow"
 
-    Check phase of state in each subrepositories, allowed values are
-    "ignore", "follow" or "abort". For settings other than "ignore",
-    the phase of each subrepository commit is checked before committing
-    in the parent repository. If there is any greater phase than the parent
-    ("secret" vs "draft", for example), the commit is either aborted
-    with "abort" or the higher phase is used with "follow". Default: "follow".
 
 ``profiling``
 -------------

--- a/tests/test-rebase-scenario-global.t	Fri Jan 31 15:25:31 2014 -0200
+++ b/tests/test-rebase-scenario-global.t	Sat Feb 01 14:53:52 2014 -0600
@@ -649,3 +649,28 @@
   |/
   o  0: 'A'
   
+
+Test that rebase is not confused by $CWD disapearing during rebase (issue 4121)
+
+  $ cd ..
+  $ hg init cwd-vanish
+  $ cd cwd-vanish
+  $ touch initial-file
+  $ hg add initial-file
+  $ hg commit -m 'initial commit'
+  $ touch dest-file
+  $ hg add dest-file
+  $ hg commit -m 'dest commit'
+  $ hg up 0
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ touch other-file
+  $ hg add other-file
+  $ hg commit -m 'first source commit'
+  created new head
+  $ mkdir subdir
+  $ cd subdir
+  $ touch subfile
+  $ hg add subfile
+  $ hg commit -m 'second source with subdir'
+  $ hg rebase -b . -d 1 --traceback
+  saved backup bundle to $TESTTMP/cwd-vanish/.hg/strip-backup/779a07b1b7a0-backup.hg (glob)