wireproto: add out-of-band error class to allow remote repo to report errors Older clients will still print the provided error message and not much else: over ssh, this will be each line prefixed with 'remote: ' in addition to an "abort: unexpected response: '\n'"; over http, this will be the '---%<---' banners in addition to the 'does not appear to be a repository' message. Currently, clients with this patch will display 'abort: remote error:\n' and the provided error text, but it is trivial to style the error text however is deemed appropriate.

--- a/mercurial/httprepo.py	Wed Aug 03 16:41:14 2011 -0500
+++ b/mercurial/httprepo.py	Tue Aug 02 15:21:10 2011 -0400
@@ -136,6 +136,8 @@
             proto = resp.headers.get('content-type', '')
 
         safeurl = util.hidepassword(self._url)
+        if proto.startswith('application/hg-error'):
+            raise error.OutOfBandError(resp.read())
         # accept old "text/plain" and "application/hg-changegroup" for now
         if not (proto.startswith('application/mercurial-') or
                 proto.startswith('text/plain') or