Fix quoting tests on Windows.

Quoting should be done with double quotes, not single quotes.

IPython/core/tests/test_completer.py

@@ -38,10 +38,10 b' def greedy_completion():'
 def test_protect_filename():
     if sys.platform == 'win32':
         pairs = [ ('abc','abc'),
-                (' abc',"' abc'"),
-                ('a bc',"'a bc'"),
-                ('a  bc',"'a  bc'"),
-                ('  bc',"'  bc'"),
+                 (' abc','" abc"'),
+                 ('a bc','"a bc"'),
+                 ('a  bc','"a  bc"'),
+                 ('  bc','"  bc"'),
                 ]
     else:
         pairs = [ ('abc','abc'),
@@ -49,7 +49,7 b' def test_protect_filename():'
                 ('a bc',r'a\ bc'),
                 ('a  bc',r'a\ \ bc'),
                 ('  bc',r'\ \ bc'),
-                # On posix, we also protect parens and other special characters
+                 # On posix, we also protect parens and other special characters.
                 ('a(bc',r'a\(bc'),
                 ('a)bc',r'a\)bc'),
                 ('a( )bc',r'a\(\ \)bc'),