https://bz.mercurial-scm.org/show_bug.cgi?id=6954

--- mercurial-6.9.1/tests/run-tests.py.orig
+++ mercurial-6.9.1/tests/run-tests.py
@@ -2402,7 +2402,7 @@
             # bypass the TextTestResult method as do deal with the output ourself
             super(base_class, self).addSuccess(test)
             if self.showAll:
-                self._write_status(test, "ok")
+                self.stream.writeln('ok')
             elif self.dots:
                 self._write_dot('.')
         self.successes.append(test)
@@ -2410,7 +2410,7 @@
     def addError(self, test, err):
         super(base_class, self).addError(test, err)
         if self.showAll:
-            self._write_status(test, "ERROR")
+            self.stream.writeln('ERROR')
         elif self.dots:
             self._write_dot('E')
         if self._options.first: