tests/test-execute-bit.t

sshpeer: move URL validation out of sshpeer.__init__

We will soon have another SSH peer class to support the new version
of the SSH protocol. However, we won't know which peer class to
instantiate until we perform a handshake on an active connection.
This means that we need to move connection establishment and handshake
code out of sshpeer.__init__.

This commit starts the process of migrating peer creation code
out of sshpeer.__init__ into instance(), which is the API for
creating peers.

The moved code no longer calls _abort(). _abort() runs _cleanup() and
raises. _cleanup() only performs actions on self._pipe*. These objects
aren't instantiated until we actually connect to the peer. So _abort()
was not necessary in the old code.

To keep the API the same, __init__() now makes a redundant call to
util.url(). This will be fixed in subsequent commits.

Differential Revision: https://phab.mercurial-scm.org/D2027

#require execbit

  $ hg init
  $ echo a > a
  $ hg ci -Am'not executable'
  adding a

  $ chmod +x a
  $ hg ci -m'executable'
  $ hg id
  79abf14474dc tip

Make sure we notice the change of mode if the cached size == -1:

  $ hg rm a
  $ hg revert -r 0 a
  $ hg debugstate
  n   0         -1 unset               a
  $ hg status
  M a

  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg id
  d69afc33ff8a
  $ test -x a && echo executable -- bad || echo not executable -- good
  not executable -- good