patch.
-- [[chrysn]]
+
+> update 2014-06-29: the problem persists, but i found it is not trivial to
+> reproduce. to demonstrate, use this test plugin:
+>
+> #!/usr/bin/env python
+> # -*- coding: utf-8 -*-
+>
+> from proxy import IkiWikiProcedureProxy
+>
+> def preprocess(self, proxy, *args):
+> return repr(self.rpc('pagetype', 'schön'))
+>
+> proxy = IkiWikiProcedureProxy(__name__)
+> proxy.hook('preprocess', preprocess, id='testdirective')
+> proxy.run()
+>
+> note that when the 'schön' is stored in a variable, the exception changes --
+> it seems to me that the issue is related to the way exceptions are encoded.
+>
+> the suggested patch still applies and solves the issue. --[[chrysn]]
+
+>> In this patch band:
+>>
+>> - xml = _IkiWikiExtPluginXMLRPCHandler._read(in_fd).decode('utf8')
+>> + response = _IkiWikiExtPluginXMLRPCHandler._read(in_fd)
+>> + if isinstance(response, unicode):
+>> + xml = response.encode('utf8')
+>>
+>> I think you mean `response.decode`, not `response.encode`.
+>>
+>> Other than that it looks good to me. I like the use of `repr` in debug
+>> messages. --[[smcv]]
+
+>>> afaict, encode is fine there -- the relevant methods in python2 are
+>>> `unicode.encode` which gives a `str`, and `str.decode` which usually gives
+>>> a `unicode`. (i'd happily ditch python2 and port all plugins to python3,
+>>> where this is all easier, but my [[todo/vCard rendering]] still uses an
+>>> ancient module.) --[[chrysn]]