[tex-live] How to create my own "tlpretest" out of SVN repository?

[Mojca Miklavec]

Dear TL gurus,

I have a slightly weird question. How can I create my own testing
repository out of the current SVN repository? (Either the whole
repository or just a single package if that is also possible. I can
probably start from an existing repository and avoid having to build
all the packages that are already up to date. But if I can only create
a few packages of my choice and rebuild texlive.tlpdb, that would be
even more perfect.)

You don't need to tell me that this in an overkill since you are
probably right (but it's not a problem if computer can do the hard
work instead of me and I'm curious how it is done anyway), but I would
like to find a way to test some packages (ConTeXt in particular, but
probably also hyphenation patterns etc.) without having to wait for
two days, figuring out that a typo broke a fresh rebuild, wait again,
fix a tiny bug, wait again, fix a tiny bug, wait again.

(Another alternative would be to misuse TLContrib for that of course,
but I'm still eager to see some pointers in building scripts.)

Thank you,
   Mojca