Editing old log messages (r3533 in particular)

[Julian Foad]

I tried to edit a log message of a change I had recently committed, and
it failed with an error saying that editing is not enabled. Is this
intentional?

The one I want to edit is r3533, and the new text is:
[[[
Tweaks to <option> mark-up. Also, accidentally, a change to the build system,
which I subsequently reverted in r3535.

* src/en/book/ch03-advanced-topics.xml
  (svn.serverconfig.netmodel.credcache): Fix mark-up of "store-auth-creds":
    we use <literal> not <option> for run-time configuration file options.

* src/en/book/ch09-reference.xml
  Fix the use of <replaceable> mark-up when used in conjunction with
  <option>. Add a missing space before an option.

* src/tools/Makefile.base-rules
  (version): Comment out the line that appends the date to the version file,
    in order to avoid re-building the book when nothing has changed. (This
    change was not intended to be part of this commit.)
]]]

- Julian