fix win drive letter lower case logic, #9393

src/vs/base/common/uri.ts

@@ -328,10 +328,14 @@ export default class URI {
 			}
 		}
 		if (path) {
-			// lower-case windown drive letters in /C:/fff
+			// lower-case windows drive letters in /C:/fff or C:/fff
 			const m = URI._upperCaseDrive.exec(path);
 			if (m) {
-				path = m[1] + m[2].toLowerCase() + path.substr(m[1].length + m[2].length);
+				if (m[1]) {
+					path = '/' + m[2].toLowerCase() + path.substr(3); // "/c:".length === 3
+				} else {
+					path = m[2].toLowerCase() + path.substr(2); // // "c:".length === 2
+				}
 			}
 
 			// encode every segement but not slashes

src/vs/base/test/common/uri.test.ts

@@ -325,6 +325,11 @@ suite('URI', () => {
 		assert.equal(value.toString(), 'file://sh%C3%A4res/path');
 	});
 
+	test('URI#toString, lower-case windows drive letter', () => {
+		assert.equal(URI.parse('untitled:c:/Users/jrieken/Code/abc.txt').toString(), 'untitled:c%3A/Users/jrieken/Code/abc.txt');
+		assert.equal(URI.parse('untitled:C:/Users/jrieken/Code/abc.txt').toString(), 'untitled:c%3A/Users/jrieken/Code/abc.txt');
+	});
+
 	test('URI#toString, escape all the bits', () => {
 
 		var value = URI.file('/Users/jrieken/Code/_samples/18500/Mödel + Other Thîngß/model.js');