extensions/git/src/git.ts/Repository/getGitRelativePath
class Repository:	async getGitRelativePath(ref: string, relativePath: string): Promise<string> {
		const relativePathLowercase = relativePath.toLowerCase();
		const dirname = path.posix.dirname(relativePath) + '/';
		const elements: { file: string; }[] = ref ? await this.lstree(ref, dirname) : await this.lsfiles(dirname);
		const element = elements.filter(file => file.file.toLowerCase() === relativePathLowercase)[0];

		if (!element) {
			throw new GitError({ message: 'Git relative path not found.' });
		}

		return element.file;
	}