Since the GStreamer dependencies in jhbuild are already built from git tags, it makes sense to just download the release tarballs instead, especially since it is then possible to use the "configure" script instead of autogen.sh and avoid problems with automake 1.13.
Chris already did that after we saw some network issues with jhbuild in the morning. *** This bug has been marked as a duplicate of bug 106552 ***
That's at least true for using the tarballs - if you wanna use configure instead of autogen, feel free to reopen.