From: "Johan Herland" <redacted>
.

_that_ SHA1. As I said, that _can_ be done with the notes
infrastructure, but - as Ted noted - there might be better solutions to
storing branch descriptions.

Is one option to store the branch description (if any) on line two of the 
<branch name> file in .git\refs\heads.
That is, from byte 42 onward, after the 40 byte sha1 and its LF.
Older systems would simply overwrite it, while newer systems would be able 
to read it. The fixed format of the first 41 chars alllows sensible checks 
in the various places it is used.

Philip Oakley