tests/test-empty-file.t

test-http-bad-server: introduce socket closing after reading a pattern

We introduce the `close-after-recv-patterns` option. It has the same goal as
`close-after-send-patterns` with a slightly different implementation.

Reading "up to a pattern" is hard. As we can only check the pattern from what we
have already read (inlike writing, were we can check what we are about to
write).

So instead we make the `close-after-recv-patterns` alter the behavior of the
existing `close-after-recv-bytes`. The value from `close-after-recv-bytes` only
gets into play after we have seen the pattern from `close-after-recv-patterns`.

This allow us to achieve the target benefit without changing the read pattern
too much.

Differential Revision: https://phab.mercurial-scm.org/D12068

  $ hg init a
  $ cd a
  $ touch empty1
  $ hg add empty1
  $ hg commit -m 'add empty1'

  $ touch empty2
  $ hg add empty2
  $ hg commit -m 'add empty2'

  $ hg up -C 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ touch empty3
  $ hg add empty3
  $ hg commit -m 'add empty3'
  created new head

  $ hg heads
  changeset:   2:a1cb177e0d44
  tag:         tip
  parent:      0:1e1d9c4e5b64
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add empty3
  
  changeset:   1:097d2b0e17f6
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add empty2
  

  $ hg merge 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

Before changeset 05257fd28591, we didn't notice the
empty file that came from rev 1:

  $ hg status
  M empty2
  $ hg commit -m merge
  $ hg manifest --debug tip
  b80de5d138758541c5f05265ad144ab9fa86d1db 644   empty1
  b80de5d138758541c5f05265ad144ab9fa86d1db 644   empty2
  b80de5d138758541c5f05265ad144ab9fa86d1db 644   empty3

  $ cd ..