lfs: avoid quadratic performance in processing server responses
This is also adapted from the Facebook repo[1]. Unlike there, we were already
reading the download stream in chunks and immediately writing it to disk, so we
basically avoided the problem on download. There shouldn't be a lot of data to
read on upload, but it's better to get rid of this pattern.
[1] https://github.com/facebookexperimental/eden/commit/
82df66ffe97e21f3ee73dfec093c87500fc1f6a7
Differential Revision: https://phab.mercurial-scm.org/D7882
$ hg init
$ touch unknown
$ touch a
$ hg add a
$ hg ci -m "1"
$ touch b
$ hg add b
$ hg ci -m "2"
Should show unknown
$ hg status
? unknown
$ hg revert -r 0 --all
removing b
Should show unknown and b removed
$ hg status
R b
? unknown
Should show a and unknown
$ ls
a
unknown