Fix thinko in addSuccess refactoring.

python/subunit/__init__.py

@@ -690,7 +690,7 @@ class TestProtocolClient(testresult.TestResult):
             self._write_details(details)
         else:
             self._stream.write(_b("\n"))
-        if details or error:
+        if details is not None or error is not None:
             self._stream.write(self._end_simple)
 
     def addSkip(self, test, reason=None, details=None):

python/subunit/details.py

@@ -85,7 +85,10 @@ class MultipartDetailsParser(DetailsParser):
             return
         # TODO error handling
         field, value = line[:-1].decode('utf8').split(' ', 1)
-        main, sub = value.split('/')
+        try:
+            main, sub = value.split('/')
+        except ValueError:
+            raise ValueError("Invalid MIME type %r" % value)
         self._content_type = content_type.ContentType(main, sub)
         self._parse_state = self._get_name