# HG changeset patch
# User Mark Drago <markdrago@gmail.com>
# Date 1299591699 18000
# Node ID 0b79cf616e650989cd129304de72b2bd2c22f9e0
# Parent  cc27c31ebc282f3fc164e513ee9bbc118034d65d
commands.update() now works properly with a revision of 0

Without this change commands.update() treats an integer 0 as if no revision
was passed and updates to the branch head.  This fix allows an integer 0 to
be detected as a revision number so the working directory is correctly
changed to revision 0 rather than the branch head.

diff -r cc27c31ebc28 -r 0b79cf616e65 mercurial/commands.py
--- a/mercurial/commands.py	Tue Mar 08 14:55:31 2011 -0600
+++ b/mercurial/commands.py	Tue Mar 08 08:41:39 2011 -0500
@@ -4053,7 +4053,7 @@
     if rev and node:
         raise util.Abort(_("please specify just one revision"))
 
-    if not rev:
+    if rev is None or rev == '':
         rev = node
 
     # if we defined a bookmark, we have to remember the original bookmark name
diff -r cc27c31ebc28 -r 0b79cf616e65 tests/test-basic.t
--- a/tests/test-basic.t	Tue Mar 08 14:55:31 2011 -0600
+++ b/tests/test-basic.t	Tue Mar 08 08:41:39 2011 -0500
@@ -20,6 +20,22 @@
   summary:     test
   
 
+Verify that updating to revision 0 via commands.update() works properly
+
+  $ cat <<EOF > update_to_rev0.py
+  > from mercurial import ui, hg, commands
+  > myui = ui.ui()
+  > repo = hg.repository(myui, path='.')
+  > commands.update(myui, repo, rev=0)
+  > EOF
+  $ hg up null
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ python ./update_to_rev0.py
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg identify -n
+  0
+ 
+
 Poke around at hashes:
 
   $ hg manifest --debug