Trac crashes if viewing in blame mode for non-ascii file name with Subversion 1.7.x

[Jun Omae]

If using Subversion 1.7.x and viewing a content in blame mode for non-ascii file name, Trac crashes by assertion svn_uri_is_canonical.

Checking for non-ascii characters in the URL is introduced in ​http://svn.apache.org/viewvc/subversion/trunk/subversion/libsvn_subr/dirent_uri.c?annotate=1064436&pathrev=1064436#l1880, 1.7.0 or later.

10:03:15 PM Trac[browser] DEBUG: Rendering preview of node Résumé.txt@None with mime-type text/plain; charset=iso-8859-15
10:03:15 PM Trac[api] DEBUG: Trying to render HTML preview using PygmentsRenderer [blame, lineno]
10:03:15 PM Trac[svn_fs] INFO: opening ra_local session to 'file:///home/jun66j5/var/svn/svnrepos.dump/t\xc3\xaate/R\xc3\xa9sum\xc3\xa9.txt'
python: subversion/libsvn_subr/dirent_uri.c:1519: uri_skip_ancestor: Assertion `svn_uri_is_canonical(child_uri, ((void *)0))' failed.
Aborted

According to ​http://svn.apache.org/viewvc/subversion/trunk/subversion/libsvn_subr/path.c?view=annotate#l821, must escape characters other than the following.

alphanum | mark | ":" | "@" | "&" | "=" | "+" | "$" | ",".