httpclient: update to 07d8c356f4d1 of py-nonblocking-http
This addresses a defect when the server closes the socket before
finishing a response (if it crashes, for example) first spotted in
Issue2951.
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