You can clone with
HTTPS or Subversion.
Since the merging of the code by @tadam to select between code for each version of GSL, we get an error like this when trying to build a new dist:
Created META.yml and META.json
Can't copy('xs/Poly_wrap.c', 'Math-GSL-0.25_02/xs/Poly_wrap.c'): No such file or directory at /home/leto/git/cxgn/local-lib/lib/perl5/Module/Build/Base.pm line 5598.
Update MANIFEST so that ./Build dist works, fixes #21