Git - don't use look-behind regex (#236447)

extensions/git/src/git.ts

@@ -502,7 +502,7 @@ export class Git {
 			const repoUri = Uri.file(repositoryRootPath);
 			const pathUri = Uri.file(pathInsidePossibleRepository);
 			if (repoUri.authority.length !== 0 && pathUri.authority.length === 0) {
-				const match = /(?<=^\/?)([a-zA-Z])(?=:\/)/.exec(pathUri.path);
+				const match = /^[\/]?([a-zA-Z])[:\/]/.exec(pathUri.path);
 				if (match !== null) {
 					const [, letter] = match;