find and merge heads in hg...

just forgot to run 'hg pull' command, so when I
committed strings and try to push, it showed eror:
----------------
hg push
/usr/lib/python2.6/site-packages/mercurial/sshrepo.py:64: DeprecationWarning: os.popen3 is deprecated. Use the subprocess module.
self.pipeo, self.pipei, self.pipee = os.popen3(cmd, 'b')
pushing to ssh://hg.mozilla.org/releases/l10n-mozilla-1.9.1/pa-IN/
searching for changes
abort: push creates new remote heads!
(did you forget to merge? use push -f to force)
----------
then try with 'hg push -f' but not get working
-----------
hg/pa-IN> hg push -f
/usr/lib/python2.6/site-packages/mercurial/sshrepo.py:64: DeprecationWarning: os.popen3 is deprecated. Use the subprocess module.
self.pipeo, self.pipei, self.pipee = os.popen3(cmd, 'b')
pushing to ssh://hg.mozilla.org/releases/l10n-mozilla-1.9.1/pa-IN/
[searching for changes
adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 13 changes to 13 files (+1 heads)
remote: Two heads detected on branch 'default'
remote: Only one head per branch is allowed!
remote: transaction abort!
remote: rollback completed
remote: abort: pretxnchangegroup.a_singlehead hook failed
abort: unexpected response: empty string

----
finally try 'hg pull', then some hints were there:
------
hg pull
pulling from http://hg.mozilla.org/releases/l10n-mozilla-1.9.1/pa-IN/
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
(run 'hg heads' to see heads, 'hg merge' to merge)
------
so, get 'hg heads', it has 3 heads, the
hg merge with 'hg merge 73a86cfb7a92'

and it is fixed and committed to last changes (local 2 central repo)

some other command, I tried:
hg tip, hg heads

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