[qtconsole] carriage-return action matches CR only, not CRLF

CarriageReturn action introduced in ipython#1089 clears a line in the qtconsole, which means that CRLF line endings would replace whole lines with '\n'.

This changes the regex to only match `\r` not followed by `\n` preventing the CR action from firing on CRLF.

Test included

closes ipython#1111

IPython/frontend/qt/console/ansi_code_processor.py

@@ -38,7 +38,7 @@
 OSC_SUBPATTERN = '\](.*?)[\x07\x1b]'
 ANSI_PATTERN = ('\x01?\x1b(%s|%s)\x02?' % \
                 (CSI_SUBPATTERN, OSC_SUBPATTERN))
-ANSI_OR_SPECIAL_PATTERN = re.compile('(\b|\r)|(?:%s)' % ANSI_PATTERN)
+ANSI_OR_SPECIAL_PATTERN = re.compile('(\b|\r(?!\n))|(?:%s)' % ANSI_PATTERN)
 SPECIAL_PATTERN = re.compile('([\f])')
 
 #-----------------------------------------------------------------------------

IPython/frontend/qt/console/tests/test_ansi_code_processor.py

@@ -105,12 +105,21 @@ def test_formfeed(self):
     def test_carriage_return(self):
         """ Are carriage return characters processed correctly?
         """
-        string = 'foo\rbar' # form feed
+        string = 'foo\rbar' # carriage return
         self.assertEquals(list(self.processor.split_string(string)), ['foo', '', 'bar'])
         self.assertEquals(len(self.processor.actions), 1)
         action = self.processor.actions[0]
         self.assertEquals(action.action, 'carriage-return')
 
+    def test_carriage_return_newline(self):
+        """transform CRLF to LF"""
+        string = 'foo\rbar\r\ncat\r\n' # carriage return and newline
+        # only one CR action should occur, and '\r\n' should transform to '\n'
+        self.assertEquals(list(self.processor.split_string(string)), ['foo', '', 'bar\r\ncat\r\n'])
+        self.assertEquals(len(self.processor.actions), 1)
+        action = self.processor.actions[0]
+        self.assertEquals(action.action, 'carriage-return')
+
     def test_beep(self):
         """ Are beep characters processed correctly?
         """