How to check out the openjdk source code from the mercurial repositories

[Fredrik Öhrström]

I think it is important that a recent stock mercurial install
can check out the full openjdk with a single clone
command.

I.e. you should not have to install special extensions just
to get the source code.

There are several ways this can be solved. But before
we dive into discussions on the possible alternatives,
I would like to see who else think it is a good idea.

Clearly, comments from people outside of Oracle
are the most important!

(When the source is checked out, then there can be
mercurial extensions in the checked out source code
for example jcheck that assists in sanity tests before
committing. So this does not limit the actual extensions
used later. Only that we should not "improve" on the versioning
part of mercurial.)

//Fredrik