Heads from merged branches

[anatoly techtonik]

Hi,

I am using Mercurial 2.6.3 on Ubuntu. Why it keeps showing me commit
from inactive merged branch in heads? Is it really necessary, or a
bug?

$ hg log --graph -r 187:190
o  changeset:   190:98f3db1ee094
|  user:        tk0miya <i.tkomiya at gmail.com>
|  date:        Sun Dec 01 16:47:18 2013 +0900
|  summary:     Update bootstrap.py to newest
|
o    changeset:   189:824acd1895fb
|\   parent:      187:772b899db726
| |  parent:      188:b0db6cd86d61
| |  user:        tk0miya <i.tkomiya at gmail.com>
| |  date:        Sun Dec 01 19:35:17 2013 +0900
| |  summary:     Merge PR #5
| |
| o  changeset:   188:b0db6cd86d61
|/   branch:      twitter-bootstrap
|    user:        yuitowest <yuitowest at gmail.com>
|    date:        Sat Nov 30 17:32:31 2013 +0900
|    summary:     Change design to Twitter Bootstrap
|
o  changeset:   187:772b899db726
|  user:        tk0miya <i.tkomiya at gmail.com>
|  date:        Thu Oct 24 18:28:32 2013 +0900
|  summary:     Fix graphviz does not support %uxxxx encode


$ hg heads
changeset:   200:b99f76060402
tag:         tip
user:        anatoly techtonik <techtonik at gmail.com>
date:        Wed Nov 20 09:17:29 2013 +0300
summary:     Add readme.md with link to online demo site.

changeset:   188:b0db6cd86d61
branch:      twitter-bootstrap
user:        yuitowest <yuitowest at gmail.com>
date:        Sat Nov 30 17:32:31 2013 +0900
summary:     Change design to Twitter Bootstrap


$ hg branch
default

$ hg branches
default                      200:b99f76060402
twitter-bootstrap            188:b0db6cd86d61 (inactive)


Please CC.
--
anatoly t.