While the logic we have been using to guess which variant of SSH
implementation is in use by looking at the name of the program has
been robust enough for GIT_SSH (which does not go through the shell,
hence it can only spell the name the SSH program and nothing else),
extending it to GIT_SSH_COMMAND and core.sshcommand opens it for
larger chance of misidentification, because these can specify
arbitrary shell command, and a simple "the first word on the line
must be the command name" heuristic may not even look at the command
name at all.

As any effort to improve the heuristic will give us only diminishing
returns, and especially given that most of the users are expected to
have a command line for which the heuristic would work correctly,
give an explicit escape hatch to override a misidentification, just
in case one happens.

It is arguably bad to add this new variable to the core.* set, in
the sense that you'll never see this variable if you do not interact
with other repositories over ssh, but core.sshcommand is already
there for some reason, so let's match it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

One of these two may have originally been named after "what exact
SSH implementation do we have" so that we can tweak the command line
options, but these days "putty=1" no longer means "We are using the
plink SSH implementation that comes with PuTTY".  It is set when we
guess that either PuTTY plink or Tortoiseplink is in use.

Rename them after what effect is desired.  The current "putty"
option is about using "-P <port>" when OpenSSH would use "-p <port>",
so rename it to port_option whose value is either 'p' or 'P".  The
other one is about passing an extra command line option "-batch",
so rename it needs_batch.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Git for Windows has special support for the popular SSH client PuTTY:
when using PuTTY's non-interactive version ("plink.exe"), we use the -P
option to specify the port rather than OpenSSH's -p option. TortoiseGit
ships with its own, forked version of plink.exe, that adds support for
the -batch option, and for good measure we special-case that, too.

However, this special-casing of PuTTY only covers the case where the
user overrides the SSH command via the environment variable GIT_SSH
(which allows specifying the name of the executable), not
GIT_SSH_COMMAND (which allows specifying a full command, including
additional command-line options).

When users want to pass any additional arguments to (Tortoise-)Plink,
such as setting a private key, they are required to either use a shell
script named plink or tortoiseplink or duplicate the logic that is
already in Git for passing the correct style of command line arguments,
which can be difficult, error prone and annoying to get right.

This patch simply reuses the existing logic and expands it to cover
GIT_SSH_COMMAND, too.

Note: it may look a little heavy-handed to duplicate the entire
command-line and then split it, only to extract the name of the
executable. However, this is not a performance-critical code path, and
the code is much more readable this way.

Signed-off-by: Segev Finer <segev208@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Code clean-up.

* ws/request-pull-code-cleanup:
  request-pull: drop old USAGE stuff

Documentation fix.

* rh/diff-orderfile-doc:
  diff: document the format of the -O (diff.orderFile) file
  diff: document behavior of relative diff.orderFile

Test clean-up.

* sb/cd-then-git-can-be-written-as-git-c:
  lib-submodule-update.sh: reduce use of subshell by using "git -C"

Documentation fix.

* ad/bisect-terms:
  Documentation/bisect: improve on (bad|new) and (good|bad)

The prereleaseSuffix feature of version comparison that is used in
"git tag -l" did not correctly when two or more prereleases for the
same release were present (e.g. when 2.0, 2.0-beta1, and 2.0-beta2
are there and the code needs to compare 2.0-beta1 and 2.0-beta2).

* sg/fix-versioncmp-with-common-suffix:
  versioncmp: generalize version sort suffix reordering
  versioncmp: factor out helper for suffix matching
  versioncmp: use earliest-longest contained suffix to determine sorting order
  versioncmp: cope with common part overlapping with prerelease suffix
  versioncmp: pass full tagnames to swap_prereleases()
  t7004-tag: add version sort tests to show prerelease reordering issues
  t7004-tag: use test_config helper
  t7004-tag: delete unnecessary tags with test_when_finished

"git diff" learned diff.interHunkContext configuration variable
that gives the default value for its --inter-hunk-context option.

* vn/diff-ihc-config:
  diff: add interhunk context config option