env: make prepend_path ignore system paths

`ENV.prepend_path "PATH", which("emacs").dirname` in the emacs
requirement was causing us to end up invoking /usr/bin/clang instead
of /usr/local/Homebrew/Library/Homebrew/shims/super/clang.

1 files changed, 4 insertions, 4 deletions

diff --git a/Library/Homebrew/test/ENV_spec.rb b/Library/Homebrew/test/ENV_spec.rb
index 7b50ca1d4..07f6cdb6b 100644
--- a/Library/Homebrew/test/ENV_spec.rb
+++ b/Library/Homebrew/test/ENV_spec.rb
@@ -115,11 +115,11 @@ shared_examples EnvActivation do
 
   describe "#prepend_path" do
     it "prepends to a path" do
-      subject.prepend_path "FOO", "/usr/bin"
-      expect(subject["FOO"]).to eq("/usr/bin")
+      subject.prepend_path "FOO", "/usr/libexec"
+      expect(subject["FOO"]).to eq("/usr/libexec")
 
-      subject.prepend_path "FOO", "/bin"
-      expect(subject["FOO"]).to eq("/bin#{File::PATH_SEPARATOR}/usr/bin")
+      subject.prepend_path "FOO", "/usr"
+      expect(subject["FOO"]).to eq("/usr#{File::PATH_SEPARATOR}/usr/libexec")
     end
   end