Merge branch 'jk/git-connection-deadlock-fix' into maint-1.7.4

[git.git] / Documentation / git-bisect.txt

diff --git a/Documentation/git-bisect.txt b/Documentation/git-bisect.txt
index 47e8b1ed66087bf6d2e33969ea7ea2d32b620393..c443e0f30767930f45ae0de53829a9b88240df6f 100644 (file)
--- a/Documentation/git-bisect.txt
+++ b/Documentation/git-bisect.txt
@@ -241,7 +241,12 @@ exit(3) manual page), as the value is chopped with "& 0377".
 
 The special exit code 125 should be used when the current source code
 cannot be tested. If the script exits with this code, the current
-revision will be skipped (see `git bisect skip` above).
+revision will be skipped (see `git bisect skip` above). 125 was chosen
+as the highest sensible value to use for this purpose, because 126 and 127
+are used by POSIX shells to signal specific error status (127 is for
+command not found, 126 is for command found but not executable---these
+details do not matter, as they are normal errors in the script, as far as
+"bisect run" is concerned).
 
 You may often find that during a bisect session you want to have
 temporary modifications (e.g. s/#define DEBUG 0/#define DEBUG 1/ in a
@@ -294,6 +299,39 @@ It is safer if both "test.sh" and "check_test_case.sh" are
 outside the repository to prevent interactions between the bisect,
 make and test processes and the scripts.
 
+* Automatically bisect with temporary modifications (hot-fix):
++
+------------
+$ cat ~/test.sh
+#!/bin/sh
+
+# tweak the working tree by merging the hot-fix branch
+# and then attempt a build
+if     git merge --no-commit hot-fix &&
+       make
+then
+       # run project specific test and report its status
+       ~/check_test_case.sh
+       status=$?
+else
+       # tell the caller this is untestable
+       status=125
+fi
+
+# undo the tweak to allow clean flipping to the next commit
+git reset --hard
+
+# return control
+exit $status
+------------
++
+This applies modifications from a hot-fix branch before each test run,
+e.g. in case your build or test environment changed so that older
+revisions may need a fix which newer ones have already. (Make sure the
+hot-fix branch is based off a commit which is contained in all revisions
+which you are bisecting, so that the merge does not pull in too much, or
+use `git cherry-pick` instead of `git merge`.)
+
 * Automatically bisect a broken test case:
 +
 ------------