hgweb: handle exception of misconfigured path on index page
If hgweb.config contains wrong path mapping, hgweb causes internal server
error on repository index page.
This patch changes makeindex() to ignore RepoError, because it looks to be
designed to suppress configuration error.
% reverting to rev 0
reverting foo
M foo
diff --git a/foo b/foo
old mode 100755
new mode 100644