rebase--am: use --cherry-pick instead of --ignore-if-in-upstream

When using `git format-patch --ignore-if-in-upstream` we are only
allowed to give a single revision range.  In the next commit we will
want to add an additional exclusion revision in order to handle fork
points correctly, so convert `git-rebase--am` to use a symmetric
difference with `--cherry-pick --right-only`.

This does not change the result of the format-patch invocation, just how
we spell the arguments.

Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
rebase: omit patch-identical commits with --fork-point

When the `--fork-point` argument was added to `git rebase`, we changed
the value of $upstream to be the fork point instead of the point from
which we want to rebase.  When $orig_head..$upstream is empty this does
not change the behaviour, but when there are new changes in the upstream
we are no longer checking if any of them are patch-identical with
changes in $upstream..$orig_head.

Fix this by introducing a new variable to hold the fork point and using
this to restrict the range as an extra (negative) revision argument so
that the set of desired revisions becomes (in fork-point mode):

	git rev-list --cherry-pick --right-only \
		$upstream...$orig_head ^$fork_point

This allows us to correctly handle the scenario where we have the
following topology:

	    C --- D --- E  <- dev
	   /
	  B  <- master@{1}
	 /
	o --- B' --- C* --- D*  <- master

where:
- B' is a fixed-up version of B that is not patch-identical with B;
- C* and D* are patch-identical to C and D respectively and conflict
  textually if applied in the wrong order;
- E depends textually on D.

The correct result of `git rebase master dev` is that B is identified as
the fork-point of dev and master, so that C, D, E are the commits that
need to be replayed onto master; but C and D are patch-identical with C*
and D* and so can be dropped, so that the end result is:

	o --- B' --- C* --- D* --- E  <- dev

If the fork-point is not identified, then picking B onto a branch
containing B' results in a conflict and if the patch-identical commits
are not correctly identified then picking C onto a branch containing D
(or equivalently D*) results in a conflict.

This change allows us to handle both of these cases, where previously we
either identified the fork-point (with `--fork-point`) but not the
patch-identical commits *or* (with `--no-fork-point`) identified the
patch-identical commits but not the fact that master had been rewritten.

Reported-by: Ted Felix <ted@tedfelix.com>
Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'jk/rebase-am-fork-point' into pu

* jk/rebase-am-fork-point:
  rebase: omit patch-identical commits with --fork-point
  rebase--am: use --cherry-pick instead of --ignore-if-in-upstream
usage: make error functions a stack

Let error routine be a stack of error functions so that callers can
temporarily override the error_routine and then pop their modification
off the stack. This enables customizing error for a small code segment.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
tag: fix --sort tests to use cat<<-\EOF format

The --sort tests should use the better format for >expect to maintain
indenting and ensure that no substitution is occurring. This makes
parsing and understanding the tests a bit easier.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
tag: update parsing to be more precise regarding errors

Update the parsing of sort string specifications so that it is able to
properly detect errors in the function type and allowed atoms.

Cc: Jeff King <peff@peff.net>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
tag: support configuring --sort via .gitconfig

Add support for configuring default sort specification for git tags.
Command line option will override the configured value. Both methods use
the same syntax. Make use of (set/pop)_error_routine to temporarily
modify error reporting when parsing as a configuration option.

Cc: Jeff King <peff@peff.net>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
SQUASH???
Merge branch 'jk/tag-sort-2' into pu

* jk/tag-sort-2:
  SQUASH???
  tag: support configuring --sort via .gitconfig
  tag: update parsing to be more precise regarding errors
  tag: fix --sort tests to use cat<<-\EOF format
  usage: make error functions a stack

Conflicts:
	builtin/tag.c