doc: identify/refer to source of each fixed bug in log and in NEWS

* HACKING (Commit log requirements): Describe our policy: when you
fix a bug, put the "git describe" string of the bug-introducing commit
in your commit log and put the "fixed-in-release version number"
in the NEWS blurb.

diff --git a/HACKING b/HACKING
index b05fd54..f8d3a9b 100644 (file)
--- a/HACKING
+++ b/HACKING
@@ -232,6 +232,17 @@ Try to make the summary line fit one of the following forms:
   build: change-description
   maint: change-description
 
+If your commit fixes a bug, try to find the commit that introduced that
+bug.  If you do that, add a note in your new commit log saying something
+like "Introduced by commit v8.12-103-g54cbe6e." and add something like
+[bug introduced in coreutils-8.13] in the corresponding NEWS blurb.
+Assuming you found the bug in commit 54cbe6e6, "git describe 54cbe6e6"
+will print the longer tag-relative string that you'll need.
+Note that we used to use an 8-byte SHA1 prefix like "54cbe6e6", because
+that was automatically rendered as a clickable link by "gitk", but with
+git-1.7.10, the more descriptive version-containing "git describe" format
+that we now require is also highlighted.
+
 
 Curly braces: use judiciously
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