tests/test-merge-subrepos.t

sslutil: store and use hostname and ui in socket instance

Currently, we pass a hostname and ui to sslutil.wrap_socket()
then create a separate sslutil.validator instance also from
a hostname and ui. There is a 1:1 mapping between a wrapped
socket and a validator instance. This commit lays the groundwork
for making the validation function generic by storing the
hostname and ui instance in the state dict attached to the
socket instance and then using these variables in the
validator function.

Since the arguments to sslutil.validator.__init__ are no longer
used, we make them optional and make __init__ a no-op.

  $ hg init

  $ echo a > a
  $ hg ci -qAm 'add a'

  $ hg init subrepo
  $ echo 'subrepo = http://example.net/libfoo' > .hgsub
  $ hg ci -qAm 'added subrepo'

  $ hg up -qC 0
  $ echo ax > a
  $ hg ci -m 'changed a'
  created new head

  $ hg up -qC 1
  $ cd subrepo
  $ echo b > b
  $ hg add b
  $ cd ..

Should fail, since there are added files to subrepo:

  $ hg merge
  abort: uncommitted changes in subrepository 'subrepo'
  [255]