git-svn: allow git-svn fetching to work using serf
When attempting to git-svn fetch files from an svn https?: url using
the serf library (the only choice starting with svn 1.8) the following
errors can occur:
Temp file with moniker 'svn_delta' already in use at Git.pm line 1250
Temp file with moniker 'git_blob' already in use at Git.pm line 1250
David Rothenberger <daveroth@acm.org> has determined the cause to
be that ra_serf does not drive the delta editor in a depth-first
manner [...]. Instead, the calls come in this order: