r27729 breaks API of svn_ra_get_log2

Hi!

I haven't seen this in real life yet, but I believe r27737 introduced an
inconsistency with the API spec. Accoding to svn_ra.h, the paths
parameter of svn_ra_get_log2 may be NULL, but as of that patch, the
implementation in ra_loader.c dereferences paths in paths->nelts without
checking for NULL first.

Do you agree this is a bug?
Would you like to see this in the issue tracker?

For those particularly interested: I found this while toying around with
bzr-svn, which suffers quite a bit from the checks in r27737.

Greetings,
  Martin von Gagern