1.5.0-rc4 up for signing/testing

It's Earth Day, and I'm pleased to announce that a 100% recyclable
Subversion 1.5.0-rc4 is up for testing and signing. The magic revision
is r30753.

http://orac.ece.utexas.edu/pub/svn/1.5.0-rc4/

As usual, signatures from full committers back to me, and enthusiastic
tester feedback is welcome. At this point, this candidate is not yet
blessed for wide release, so please don't make it available to people
not interested in test-driving the new release.

Distro package maintainers, please do NOT include any pre-release
builds, even blessed, into operating system distros. The reasons for
not doing so were very eloquently outlined by Karl in a mail, which is
summarized at the above address.

The quick version is: we don't guarantee compatibility between the
pre-releases and the final release, so if people install the release
candidate, all their repositories and working copies might break
unrepairably when they upgrade to 1.5.0 proper. We don't want that kind
of bad publicity, and neither do you.

Let's get this tested, signed and released, so we can start the 1.5 soak!

-Hyrum