Fix recognition of reviewers in commit message tags

A bug in JGit's footer match method caused "Sample-Bug-Id: 42"
to be treated identical to the footer line "Signed-off-by: 42".

Since Signed-off-by tags are converted into reviewers, we were adding
account number 42 as a reviewer anytime we saw "Sample-Bug-Id: 42".
This happened for any footer line key, so long as its length matched
the length of "Signed-off-by".

This was fixed in a newer version of JGit, so upgrade.

Also prevent "Signed-off-by: 42" from being treated as an account.
Within a commit message, we only want to match to a reviewer by
their full name or their email address.  Matching on their internal
database id number isn't useful.

Bug: issue 553
Change-Id: Ie26974240f26d29fb55cd95dc6b6c72c89903f37
Signed-off-by: Shawn O. Pearce <sop@google.com>
diff --git a/ReleaseNotes/ReleaseNotes-2.1.2.4.txt b/ReleaseNotes/ReleaseNotes-2.1.2.4.txt
index c651b69..f96c74a 100644
--- a/ReleaseNotes/ReleaseNotes-2.1.2.4.txt
+++ b/ReleaseNotes/ReleaseNotes-2.1.2.4.txt
@@ -25,7 +25,13 @@
 ISO-8859-1 character set is used as a fallback, so the file content
 is still visible.
 
-* Update JGit to 0.7.1.34-gf36df5d to fix empty tree bug
+* issue 553 Bugs sometimes added as change reviewers
++
+Bug references were sometimes added as an 'Anonymous Coward' change
+reviewer when the line used to mention the bug in the commit message
+was the same length as 'Signed-off-by'.  Fixed.
+
+* Update JGit to 0.7.1.46-gdd63f5c to fix empty tree bug
 +
 Repositories which contained an empty tree object (very uncommon, its
 technically a bug to produce a repository like this) wouldn't clone