Use bash instead.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142486 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/release/test-release.sh b/utils/release/test-release.sh
index 642933e..00a1ac1 100755
--- a/utils/release/test-release.sh
+++ b/utils/release/test-release.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env bash
 #===-- test-release.sh - Test the LLVM release candidates ------------------===#
 #
 #                     The LLVM Compiler Infrastructure