Cleanups from review.

Detect pip installs with 'bdist_wheel' (or manual builds for upload) and don't let the C extensions fail to build unless PURE_PYTHON is set.

BTrees/_compat.py

@@ -85,9 +85,10 @@ def import_c_extension(mod_globals):
         new_values.pop('__doc__', None)
         mod_globals.update(new_values)
     else:
-        # No C extension,
-        # make the Py versions available without that extension
-        for py in [k for k in mod_globals.keys() if k.endswith('Py')]:
+        # No C extension, make the Py versions available without that
+        # extension. The list comprehension both filters and prevents
+        # concurrent modification errors.
+        for py in [k for k in mod_globals if k.endswith('Py')]:
             mod_globals[py[:-2]] = mod_globals[py]
 
     # Assign the global aliases

BTrees/tests/common.py

@@ -2302,7 +2302,6 @@ class ConflictTestBase(object):
         super(ConflictTestBase, self).setUp()
         _skip_if_pure_py_and_py_test(self)
 
-
     def tearDown(self):
         import transaction
         transaction.abort()

BTrees/tests/testBTreesUnicode.py

@@ -38,7 +38,7 @@ class TestBTreesUnicode(unittest.TestCase):
                      (b'future', 4),
                      (b'quick', 5),
                      (b'zerst\xf6rt', 6),
-                     (b'dreit\xe4gigen'.decode('latin1'), 7),
+                     (u'dreit\xe4gigen', 7),
                     ]
 
         self.tree = OOBTree()

setup.py

@@ -11,10 +11,11 @@
 # FOR A PARTICULAR PURPOSE.
 #
 ##############################################################################
-
+from __future__ import print_function
 __version__ = '4.4.1'
 
 import os
+import sys
 
 from distutils.errors import CCompilerError
 from distutils.errors import DistutilsExecError
@@ -59,6 +60,11 @@ class optional_build_ext(build_ext):
         print()
         print(e)
         print('*' * 80)
+        if 'bdist_wheel' in sys.argv and not os.environ.get("PURE_PYTHON"):
+            # pip uses bdist_wheel by default, and hides the error output.
+            # Let this error percolate up so the user can see it.
+            # pip will then go ahead and run 'setup.py install' directly.
+            raise
 
 # Include directories for C extensions
 # Sniff the location of the headers in 'persistent' or fall back

tox.ini

@@ -32,7 +32,7 @@ setenv =
 basepython =
     python2.7
 deps =
-	{[testenv]deps}
+    {[testenv]deps}
     ZODB
 
 [testenv:coverage]