Error messages for non-svn URLs are cryptic

   I accidentally gave someone the wrong URL and they got errors which
confused the hell out of them. A couple of examples follow.

Attempt to check out a plain HTTP URL:

[pucca:/tmp] wsanchez% svn co http://foo.apple.com/foo/bar
subversion/libsvn_ra_dav/util.c:670: (apr_err=175002)
svn: PROPFIND request failed on '/foo/bar'
subversion/libsvn_ra_dav/util.c:294: (apr_err=175002)
svn: PROPFIND of '/foo/bar': 405 Method Not Allowed
(http://foo.apple.com)

Attempt to check out a WebDAV URL:

[pucca:/tmp] wsanchez% svn co http://foo.apple.com/dav/
subversion/libsvn_ra_dav/util.c:670: (apr_err=175002)
svn: PROPFIND request failed on '/dav'
subversion/libsvn_ra_dav/util.c:294: (apr_err=175002)
svn: PROPFIND of '/dav': 301 Moved Permanently (http://foo.apple.com)

   These make sense to svn developers, and might make sense to the
repository admins and maybe web server admins using subversion, but
they don't really tell you the obvious thing: the provided URL is not a
URL to a Subversion repository.

   The first error (405) is pretty clear to a web admin; I screwed up
the access controls. The second is the one that happened in our case
and it threw me for a loop until I realized that it was the wrong URL.

   Perhaps these could be made clearer.

     -wsv