write: add the possibility to pass keyword argument from batchget to vfs
We are going to pass atomictemp keyword argument from merge.baychget to
vfs.__call__. Update all the frames to accept **kwargs and pass it to the next
function.
Differential Revision: https://phab.mercurial-scm.org/D1881
$ rm -rf a
$ hg init a
$ cd a
$ echo a > a
$ hg ci -Am0
adding a
$ hg tag t1 # 1
$ hg tag --remove t1 # 2
$ hg co 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg tag -f -r0 t1
$ hg tags
tip 3:a49829c4fc11
t1 0:f7b1eb17ad24
$ cd ..