[PATCH 4 of 4] update: use revsingle to enable use of revsets as update targets

[Augie Fackler]

# HG changeset patch
# User Augie Fackler <durin42 at gmail.com>
# Date 1286809662 18000
# Node ID abe22b13e3101f0a0b07d8c78f260ab8873d0805
# Parent  8e11ec206b83c9eb1ec0effaf100900b3b3af2e5
update: use revsingle to enable use of revsets as update targets

Fixes issue1993.

diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -3790,6 +3790,8 @@
     if not rev:
         rev = node
 
+    rev = cmdutil.revsingle(repo, rev).rev()
+
     if check and clean:
         raise util.Abort(_("cannot specify both -c/--check and -C/--clean"))
 
diff --git a/tests/test-1993.t b/tests/test-1993.t
new file mode 100644
--- /dev/null
+++ b/tests/test-1993.t
@@ -0,0 +1,46 @@
+  $ hg init a
+  $ cd a
+  $ echo a > a
+  $ hg ci -Am0
+  adding a
+  $ echo b > b
+  $ hg ci -Am1
+  adding b
+  $ hg tag -r0 default
+  warning: tag default conflicts with existing branch name
+  $ hg log
+  changeset:   2:30a83d1e4a1e
+  tag:         tip
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     Added tag default for changeset f7b1eb17ad24
+  
+  changeset:   1:925d80f479bb
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     1
+  
+  changeset:   0:f7b1eb17ad24
+  tag:         default
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     0
+  
+  $ hg update 'tag(default)'
+  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
+  $ hg parents
+  changeset:   0:f7b1eb17ad24
+  tag:         default
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     0
+  
+  $ hg update 'branch(default)'
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg parents
+  changeset:   2:30a83d1e4a1e
+  tag:         tip
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     Added tag default for changeset f7b1eb17ad24
+