1 files changed, 27 insertions, 4 deletions
diff --git a/Library/Homebrew/utils.rb b/Library/Homebrew/utils.rb
index 529f3492d..5a6295394 100644
--- a/Library/Homebrew/utils.rb
+++ b/Library/Homebrew/utils.rb
@@ -287,10 +287,9 @@ ensure
 end
 
 def run_as_not_developer(&_block)
-  old = ENV.delete "HOMEBREW_DEVELOPER"
-  yield
-ensure
-  ENV["HOMEBREW_DEVELOPER"] = old
+  with_env "HOMEBREW_DEVELOPER" => nil do
+    yield
+  end
 end
 
 # Kernel.system but with exceptions
@@ -533,3 +532,27 @@ def migrate_legacy_keg_symlinks_if_necessary
   end
   FileUtils.rm_rf legacy_pinned_kegs
 end
+
+# Calls the given block with the passed environment variables
+# added to ENV, then restores ENV afterwards.
+# Example:
+# with_env "PATH" => "/bin" do
+#   system "echo $PATH"
+# end
+#
+# Note that this method is *not* thread-safe - other threads
+# which happen to be scheduled during the block will also
+# see these environment variables.
+def with_env(hash)
+  old_values = {}
+  begin
+    hash.each do |key, value|
+      old_values[key] = ENV.delete(key)
+      ENV[key] = value
+    end
+
+    yield if block_given?
+  ensure
+    ENV.update(old_values)
+  end
+end