git svn show-ignore is excrutiatingly slow

[Adam Spiers <git@adamspiers.org>]

Something is badly wrong here ...

$ cd $svn_wd
$ time svn propget -R svn:ignore >/dev/null
svn propget -R svn:ignore > /dev/null  0.28s user 0.20s system 98% cpu 0.490 total
$ cd $git_wd
$ time git svn show-ignore > show-ignore.out
git svn show-ignore > show-ignore.out  20.52s user 33.69s system 1% cpu 1:23:42.17 total

That's 10,000 times slower for what is effectively the same source
tree!  Admittedly the svn propget was a "warm" run and took longer the
first time around, but even so there are several orders of magnitude
difference.

I had a quick look at the code and it seemed to be doing the svn tree
recursion itself via Git::SVN::prop_walk(), which might explain why.
However I did not have time to dig deeper, so would welcome any ideas.

Thanks,
Adam