Since it is a possibility that LDFLAGS or CPPFLAGS were set with options that

in no way affect library or include directories the code must take that into
account and not assume some options were found.

1 files changed, 3 insertions, 2 deletions

diff --git a/setup.py b/setup.py
index c8d9aa0b34..0f7b0b916d 100644
--- a/setup.py
+++ b/setup.py
@@ -270,8 +270,9 @@ class PyBuildExt(build_ext):
                 parser.error = lambda msg: None
                 parser.add_option(arg_name, dest="dirs", action="append")
                 options = parser.parse_args(env_val.split())[0]
-                for directory in options.dirs:
-                    add_dir_to_list(dir_list, directory)
+                if options.dirs:
+                    for directory in options.dirs:
+                        add_dir_to_list(dir_list, directory)
 
         if os.path.normpath(sys.prefix) != '/usr':
             add_dir_to_list(self.compiler.library_dirs,