When resolving sourcemap URL, ignore leading directory

These  may be outputted by esbuild when using its `--public-path` option

Author: gjtorikian

lib/propshaft/compiler/source_mapping_urls.rb

@@ -3,7 +3,7 @@
 require "propshaft/compiler"
 
 class Propshaft::Compiler::SourceMappingUrls < Propshaft::Compiler
-  SOURCE_MAPPING_PATTERN = %r{^(//|/\*)# sourceMappingURL=(.+\.map)}
+  SOURCE_MAPPING_PATTERN = %r{^(//|/\*)# sourceMappingURL=(?:.*\/)?(.*\.map)}
 
   def compile(logical_path, input)
     input.gsub(SOURCE_MAPPING_PATTERN) { source_mapping_url(asset_path($2, logical_path), $1) }

test/fixtures/assets/mapped/prefixed-source.js

@@ -25,6 +25,11 @@ class Propshaft::Compiler::SourceMappingUrlsTest < ActiveSupport::TestCase
                  compile_asset(find_asset("nested/another-source.js", fixture_path: "mapped"))
   end
 
+  test "resolves prefix on source map filename" do
+    assert_match %r{//# sourceMappingURL=/assets/source.js-[a-z0-9]{40}\.map},
+                 compile_asset(find_asset("prefixed-source.js", fixture_path: "mapped"))
+  end
+
   test "missing source map" do
     assert_no_match %r{sourceMappingURL},
                     compile_asset(find_asset("sourceless.js", fixture_path: "mapped"))