test-largefiles.t: fix wrong '#if hgweb' - it should be '#if serve' A bug introduced in 0c1d10351869 did that a part of the test never was run.

dispatch: show empty filename in OSError aborts Mercurial would sometimes exit with: abort: No such file or directory where str of the actual OSError exception was the more helpful: [Errno 2] No such file or directory: '' The exception will now always show the filename and quote it: abort: No such file or directory: ''