Merge pull request #1909 from jstenar/fixfor-1908

Use os.path.normcase for safe filename comparisons.

Closes  #1908.

IPython/core/tests/test_oinspect.py

@@ -54,7 +54,7 b' def test_find_source_lines():'
 # A couple of utilities to ensure these tests work the same from a source or a
 # binary install
 def pyfile(fname):
-    return re.sub('.py[co]$', '.py', fname)
+    return os.path.normcase(re.sub('.py[co]$', '.py', fname))
 
 
 def match_pyfiles(f1, f2):