Added test demonstrating issue #64

A directory hacked inside the distutils `EGG-INFO/scripts` metadata directory
(which can apparently happen in python 3.3 with a `__pycache__` directory)
breaks the current distutils script detection code.

Refs #64

src/zc/buildout/easy_install.txt

@@ -955,6 +955,19 @@ like for the console_scripts:
 Due to the nature of distutils scripts, buildout cannot pass arguments as
 there's no specific method to pass them to.
 
+In some cases, a python 3 ``__pycache__`` directory can end up in a
+distutils-internal directory. Buildout doesn't crash on that:
+
+    >>> eggname = [name for name in os.listdir(distdir2)
+    ...            if name.endswith('egg')][0]
+    >>> scripts_metadata_dir = os.path.join(
+    ...     distdir2, eggname, 'EGG-INFO', 'scripts')
+    >>> os.mkdir(os.path.join(scripts_metadata_dir, '__dummy__'))
+    >>> scripts = zc.buildout.easy_install.scripts(
+    ...     ['du_zipped'], ws, sys.executable, distbin2)
+    >>> ls(distbin2)
+    -  distutilsscript
+
 
 Handling custom build options for extensions provided in source distributions
 -----------------------------------------------------------------------------