Update: the ejabberd-modules SVN repo works correctly now.
The ejabberd-modules SVN repository doesn't work since yesterday. The problem is not yet known.
As a temporary solution to download the latest versions of files, there are Git repositories of individual ejabberd-modules projects that seem to work correctly. Example usage:
git clone http://git.process-one.net/ejabberd-modules/ejabberd-dev.git git clone http://git.process-one.net/ejabberd-modules/pgsql.git
I'll update this newspost as soon as I know when the SVN repository will be available again.
Note: the ejabberd SVN works correctly.