Added tests and comments for: https://bugs.launchpad.net/bugs/266993

This looks like it will nasty to fix as it is a bug in Pytho itself!

IPython/kernel/core/interpreter.py

@@ -679,21 +679,22 b' class Interpreter(object):'
         # to exec will fail however.  There seems to be some inconsistency in
         # how trailing whitespace is handled, but this seems to work.
         python = python.strip()
-
+        
         # The compiler module does not like unicode. We need to convert
         # it encode it:
         if isinstance(python, unicode):
             # Use the utf-8-sig BOM so the compiler detects this a UTF-8
             # encode string.
             python = '\xef\xbb\xbf' + python.encode('utf-8')
-
+        
         # The compiler module will parse the code into an abstract syntax tree.
+        # This has a bug with str("a\nb"), but not str("""a\nb""")!!!
         ast = compiler.parse(python)
-
+        
         # Uncomment to help debug the ast tree
         # for n in ast.node:
         #     print n.lineno,'->',n
-                
+        
         # Each separate command is available by iterating over ast.node. The
         # lineno attribute is the line number (1-indexed) beginning the commands
         # suite.
@@ -703,20 +704,23 b' class Interpreter(object):'
         # We might eventually discover other cases where lineno is None and have
         # to put in a more sophisticated test.
         linenos = [x.lineno-1 for x in ast.node if x.lineno is not None]
-
+        
         # When we finally get the slices, we will need to slice all the way to
         # the end even though we don't have a line number for it. Fortunately,
         # None does the job nicely.
         linenos.append(None)
+        
+        # This is causing problems with commands that have a \n embedded in
+        # a string, such as str("""a\nb""")
         lines = python.splitlines()
-
+        
         # Create a list of atomic commands.
         cmds = []
         for i, j in zip(linenos[:-1], linenos[1:]):
             cmd = lines[i:j]
             if cmd:
                 cmds.append('\n'.join(cmd)+'\n')
-
+        
         return cmds
 
     def error(self, text):

IPython/kernel/core/tests/test_interpreter.py

@@ -15,12 +15,22 b' __docformat__ = "restructuredtext en"'
 # Imports                                                                     
 #-----------------------------------------------------------------------------
 
+import unittest
 from IPython.kernel.core.interpreter import Interpreter
 
-def test_unicode():
-    """ Test unicode handling with the interpreter.
-    """
-    i = Interpreter()
-    i.execute_python(u'print "ù"')
-    i.execute_python('print "ù"')
+class TestInterpreter(unittest.TestCase):
+    
+    def test_unicode(self):
+        """ Test unicode handling with the interpreter.
+        """
+        i = Interpreter()
+        i.execute_python(u'print "ù"')
+        i.execute_python('print "ù"')
+    
+    def test_ticket266993_1(self):
+        i = Interpreter()
+        i.execute('str("""a\nb""")')
 
+    def test_ticket266993_2(self):
+        i = Interpreter()
+        i.execute('str("a\nb")')
  No newline at end of file