Disambiguate relative paths containing colons.

Author: samuel-williams-shopify

lib/protocol/url/path.rb

@@ -386,6 +386,9 @@ def relative(from)
 				# An empty reference identifies the current document, so identify the current directory explicitly:
 				if relative_segments == [""]
 					relative_segments = [".", ""]
+				elsif relative_segments.first&.include?(":")
+					# A colon in the first segment would be interpreted as a URI scheme:
+					relative_segments.unshift(".")
 				end
 
 				return Path.new(nil, relative_segments)

test/protocol/url/path.rb

@@ -521,6 +521,10 @@
 			expect(Protocol::URL::Path.relative("/docs", "/docs/index.html")).to be == "../docs"
 		end
 
+		it "disambiguates a colon in the first segment" do
+			expect(Protocol::URL::Path.relative("/docs/this:that", "/docs/index.html")).to be == "./this:that"
+		end
+		
 		it "calculates relative path with multiple levels up" do
 			expect(Protocol::URL::Path.relative("/a/file.txt", "/x/y/z/")).to be == "../../../a/file.txt"
 		end

test/protocol/url/relative.rb

@@ -224,6 +224,14 @@
 			expect(url.relative_to("/index").to_s).to be == "./?q=ruby#examples"
 		end
 
+		it "disambiguates a colon in the first segment" do
+			url = Protocol::URL::Relative.new("/docs/this:that")
+			relative_url = url.relative_to("/docs/index")
+			
+			expect(relative_url.to_s).to be == "./this:that"
+			expect(Protocol::URL[relative_url.to_s]).to be_a(Protocol::URL::Relative)
+		end
+		
 		it "returns already-relative URLs unchanged" do
 			url = Protocol::URL::Relative.new("../guide", "q=ruby", "examples")