Ensure shebang lines are correctly quoted if sys.executable contains spaces.

Fixes issue #398. This only special-cases sys.executable; if the --executable
parameter is used, paths with spaces have to be quoted there explicitly. While
this change also applies to Unix platforms, if sys.executable contains spaces
on Unix, any shebang lines created with it aren't going to work either way,
whether they are quoted or not.

setuptools/command/easy_install.py

@@ -1985,9 +1985,18 @@ class CommandSpec(list):
     def as_header(self):
         return self._render(self + list(self.options))
 
+    @staticmethod
+    def _strip_quotes(item):
+        _QUOTES = '"\''
+        for q in _QUOTES:
+            if item.startswith(q) and item.endswith(q):
+                return item[1:-1]
+        return item
+
     @staticmethod
     def _render(items):
-        cmdline = subprocess.list2cmdline(items)
+        cmdline = subprocess.list2cmdline(
+            CommandSpec._strip_quotes(item.strip()) for item in items)
         return '#!' + cmdline + '\n'
 
 # For pbr compat; will be removed in a future version.

setuptools/command/install_scripts.py

 from distutils import log
 import distutils.command.install_scripts as orig
 import os
+import sys
 
 from pkg_resources import Distribution, PathMetadata, ensure_directory
 
@@ -37,6 +38,10 @@ class install_scripts(orig.install_scripts):
         if is_wininst:
             exec_param = "python.exe"
             writer = ei.WindowsScriptWriter
+        if exec_param == sys.executable:
+            # In case the path to the Python executable contains a space, wrap
+            # it so it's not split up.
+            exec_param = [exec_param]
         # resolve the writer to the environment
         writer = writer.best()
         cmd = writer.command_spec_class.best().from_param(exec_param)