python_helper prepends PYTHONPATH

…instead of appending. This should be safer against any
malformed user-defined values in the PYTHONPATH.

1 files changed, 3 insertions, 3 deletions

diff --git a/Library/Homebrew/python_helper.rb b/Library/Homebrew/python_helper.rb
index b121ca5d7..3fd501bb2 100644
--- a/Library/Homebrew/python_helper.rb
+++ b/Library/Homebrew/python_helper.rb
@@ -1,4 +1,4 @@
-# This is used in the Formula class when the user calls
+# This helper method is used in the Formula class when the user calls
 # `python`, `python2` or `python3`.
 
 # This method has a dual nature. For one, it takes a &block and sets up
@@ -65,9 +65,9 @@ def python_helper(options={:allowed_major_versions => [2, 3]}, &block)
       # In order to install into the Cellar, the dir must exist and be in the
       # PYTHONPATH. This will be executed in the context of the formula
       # so that lib points to the HOMEBREW_PREFIX/Cellar/<formula>/<version>/lib
-      puts "brew: Appending to PYTHONPATH: #{py.site_packages}" if ARGV.verbose?
+      puts "brew: Prepending to PYTHONPATH: #{py.site_packages}" if ARGV.verbose?
       mkdir_p py.site_packages
-      ENV.append 'PYTHONPATH', py.site_packages, ':'
+      ENV.prepend 'PYTHONPATH', py.site_packages, ':'
       ENV['PYTHON'] = py.binary
       ENV.prepend 'CMAKE_INCLUDE_PATH', py.incdir, ':'
       ENV.prepend 'PKG_CONFIG_PATH', py.pkg_config_path, ':' if py.pkg_config_path