packaging: require mercurial >= 4.5
Otherwise building the doc package fails with:
(third party extension evolve requires version 4.5 or newer of Mercurial; disabling)
Exception occurred:
File "/usr/lib/python2.7/dist-packages/mercurial/help.py", line 624, in help_
raise error.Abort(msg, hint=hint)
Abort: no such help topic: evolve
-------------------------
Evolve Commands Reference
-------------------------
.. highlight:: none
amend
-----
.. hghelp:: amend
evolve
------
.. hghelp:: evolve
fold
----
.. hghelp:: fold
metaedit
--------
.. hghelp:: metaedit
next
----
.. hghelp:: next
obslog
------
.. hghelp:: obslog
pdiff
-----
.. hghelp:: pdiff
previous
--------
.. hghelp:: previous
prune
-----
.. hghelp:: prune
pstatus
-------
.. hghelp:: pstatus
split
-----
.. hghelp:: split
touch
-----
.. hghelp:: touch
uncommit
--------
.. hghelp:: uncommit