git-rev-list: add --bisect-vars option.

This adds --bisect-vars option to rev-list.  The output is suitable
for `eval` in shell and defines five variables:

 - bisect_rev is the next revision to test.
 - bisect_nr is the expected number of commits to test after
   bisect_rev is tested.
 - bisect_good is the expected number of commits to test
   if bisect_rev turns out to be good.
 - bisect_bad is the expected number of commits to test
   if bisect_rev turns out to be bad.
 - bisect_all is the number of commits we are bisecting right now.

The documentation text was partly stolen from Johannes
Schindelin's patch.

Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 13 insertions, 0 deletions

diff --git a/Documentation/git-rev-list.txt b/Documentation/git-rev-list.txt
index 4f145eaba..3fa45b81c 100644
--- a/Documentation/git-rev-list.txt
+++ b/Documentation/git-rev-list.txt
@@ -26,6 +26,7 @@ SYNOPSIS
 	     [ [\--objects | \--objects-edge] [ \--unpacked ] ]
 	     [ \--pretty | \--header ]
 	     [ \--bisect ]
+	     [ \--bisect-vars ]
 	     [ \--merge ]
 	     [ \--reverse ]
 	     [ \--walk-reflogs ]
@@ -249,6 +250,18 @@ introduces a regression is thus reduced to a binary search: repeatedly
 generate and test new 'midpoint's until the commit chain is of length
 one.
 
+--bisect-vars::
+
+This calculates the same as `--bisect`, but outputs text ready
+to be eval'ed by the shell. These lines will assign the name of
+the midpoint revision to the variable `bisect_rev`, and the
+expected number of commits to be tested after `bisect_rev` is
+tested to `bisect_nr`, the expected number of commits to be
+tested if `bisect_rev` turns out to be good to `bisect_good`,
+the expected number of commits to be tested if `bisect_rev`
+turns out to be bad to `bisect_bad`, and the number of commits
+we are bisecting right now to `bisect_all`.
+
 --
 
 Commit Ordering