Serialise Pathnames in forked child errors

Library/Homebrew/test/utils/fork_spec.rb

@@ -46,6 +46,19 @@
         )
       end
     end
+
+    it "preserves an ErrorDuringExecution with a Pathname command" do
+      error = ErrorDuringExecution.new([Pathname("/usr/bin/false"), "arg"], status: 1)
+
+      IO.pipe do |reader, writer|
+        described_class.report_forked_child_error(writer, error)
+
+        expect(described_class.rewrite_child_error(JSON.parse(reader.read))).to have_attributes(
+          class: ErrorDuringExecution,
+          cmd:   ["/usr/bin/false", "arg"],
+        )
+      end
+    end
   end
 
   describe "#safe_fork" do

Library/Homebrew/utils/fork.rb

@@ -93,6 +93,7 @@ def self.report_forked_child_error(error_pipe, error)
     coder = JSON::Coder.new do |object|
       case object
       when Exception then child_error_hash(object)
+      when Pathname then object.to_s
       else object
       end
     end