sdist command: fix case insensitivity when adding some files to filelist

This should fix the problem in Bitbucket issue #100.  It gives the same behavior
for inclusion of default files (README*, etc.) on Windows as Linux.

BACKWARDS INCOMPATABILITY:

This may result in a backwards incompatible change for users on a
case insensitive file system.  If they were relying on some files getting
included in their distribution due to setuptools defaults, and their files do not
have the same case as the files being looked for in setuptools, those files
will no longer be included in the package.

For example, if a package had a file:

readme.rst

Previous to this commit, that file would have been included in the distribution
as:

README.rst

But it will now no longer be included at all.  To get the file included in
the package, it can be added to the package's MANIFEST.in file:

include readme.rst

Files affected by this change will have a case variant of the files or
patterns listed below:

README
README.txt
README.rst
setup.py (or whatever your setuptools script is named)
setup.cfg
test/test*.py

3 files changed, 46 insertions, 4 deletions

diff --git a/setuptools/command/sdist.py b/setuptools/command/sdist.py
index 2aa1ee20..dc8d6773 100755
--- a/setuptools/command/sdist.py
+++ b/setuptools/command/sdist.py
@@ -8,6 +8,8 @@ import sys
 
 from setuptools import svn_utils
 from setuptools.compat import PY3
+from setuptools.utils import cs_path_exists
+
 import pkg_resources
 
 READMES = ('README', 'README.rst', 'README.txt')
@@ -146,7 +148,7 @@ class sdist(orig.sdist):
                 alts = fn
                 got_it = 0
                 for fn in alts:
-                    if os.path.exists(fn):
+                    if cs_path_exists(fn):
                         got_it = 1
                         self.filelist.append(fn)
                         break
@@ -155,16 +157,17 @@ class sdist(orig.sdist):
                     self.warn("standard file not found: should have one of " +
                               ', '.join(alts))
             else:
-                if os.path.exists(fn):
+                if cs_path_exists(fn):
                     self.filelist.append(fn)
                 else:
                     self.warn("standard file '%s' not found" % fn)
 
         optional = ['test/test*.py', 'setup.cfg']
         for pattern in optional:
-            files = list(filter(os.path.isfile, glob(pattern)))
+            files = list(filter(cs_path_exists, glob(pattern)))
             if files:
-                self.filelist.extend(files)
+                actual_fnames = map(os.path.normcase, files)
+                self.filelist.extend(actual_fnames)
 
         # getting python files
         if self.distribution.has_pure_modules():
diff --git a/setuptools/tests/test_sdist.py b/setuptools/tests/test_sdist.py
index 5b3862e9..5f8a190f 100644
--- a/setuptools/tests/test_sdist.py
+++ b/setuptools/tests/test_sdist.py
@@ -86,6 +86,7 @@ class TestSdistTest(unittest.TestCase):
         f = open(os.path.join(self.temp_dir, 'setup.py'), 'w')
         f.write(SETUP_PY)
         f.close()
+
         # Set up the rest of the test package
         test_pkg = os.path.join(self.temp_dir, 'sdist_test')
         os.mkdir(test_pkg)
@@ -121,6 +122,33 @@ class TestSdistTest(unittest.TestCase):
         self.assertTrue(os.path.join('sdist_test', 'b.txt') in manifest)
         self.assertTrue(os.path.join('sdist_test', 'c.rst') not in manifest)
 
+
+    def test_defaults_case_sensitivity(self):
+        """
+            Make sure default files (README.*, etc.) are added in a case-sensitive
+            way to avoid problems with packages built on Windows.
+        """
+
+        open(os.path.join(self.temp_dir, 'readme.rst'), 'w').close()
+        open(os.path.join(self.temp_dir, 'SETUP.cfg'), 'w').close()
+
+        dist = Distribution(SETUP_ATTRS)
+        # the extension deliberately capitalized for this test
+        # to make sure the actual filename (not capitalized) gets added
+        # to the manifest
+        dist.script_name = 'setup.PY'
+        cmd = sdist(dist)
+        cmd.ensure_finalized()
+
+        with quiet():
+            cmd.run()
+
+        # lowercase all names so we can test in a case-insensitive way to make sure the files are not included
+        manifest = map(lambda x: x.lower(), cmd.filelist.files)
+        self.assertFalse('readme.rst' in manifest, manifest)
+        self.assertFalse('setup.py' in manifest, manifest)
+        self.assertFalse('setup.cfg' in manifest, manifest)
+
     def test_manifest_is_written_with_utf8_encoding(self):
         # Test for #303.
         dist = Distribution(SETUP_ATTRS)
diff --git a/setuptools/utils.py b/setuptools/utils.py
new file mode 100644
index 00000000..91e4b87f
--- /dev/null
+++ b/setuptools/utils.py
@@ -0,0 +1,11 @@
+import os
+import os.path
+
+
+def cs_path_exists(fspath):
+    if not os.path.exists(fspath): 
+        return False
+    # make absolute so we always have a directory
+    abspath = os.path.abspath(fspath)
+    directory, filename = os.path.split(abspath)
+    return filename in os.listdir(directory)
\ No newline at end of file