posix: remove is-comparison between integers
Comparing integers by identity relies on a CPython implementation
detail of caching integers between -5 and 256.[1]
[1] <http://docs.python.org/c-api/int.html#PyInt_FromLong>
Minimal hgk check
$ echo "[extensions]" >> $HGRCPATH
$ echo "hgk=" >> $HGRCPATH
$ hg init repo
$ cd repo
$ echo a > a
$ hg ci -Am adda
adding a
$ hg debug-cat-file commit 0
tree a0c8bcbbb45c
parent 000000000000
author test 0 0
committer test 0 0
revision 0
branch default
adda