infinitepush: drop logic related to treemanifest extension
treemanifest is another facebook's extension which is not in core. Let's drop
the logic related to infinitepush extension which is now ported to core.
Differential Revision: https://phab.mercurial-scm.org/D2106
#require symlink
https://bz.mercurial-scm.org/1438
$ hg init
$ ln -s foo link
$ hg add link
$ hg ci -mbad link
$ hg rm link
$ hg ci -mok
$ hg diff -g -r 0:1 > bad.patch
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg import --no-commit bad.patch
applying bad.patch
$ hg status
R link
? bad.patch