From 627fc5b44f7c5fab2d6bc81ae3a0d9b06cb9f3bf Mon Sep 17 00:00:00 2001
From: Tetragramm <gaussgun+github@gmail.com>
Date: Mon, 29 Jul 2019 18:17:49 -0500
Subject: ExternalProject: Avoid unnecessary checkout on clone

The clone step checks out the cloned branch but is always followed by an
explicit checkout of the desired `GIT_TAG`.  Tell `git clone` not to
check out.
---
 Modules/ExternalProject.cmake | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Modules/ExternalProject.cmake b/Modules/ExternalProject.cmake
index 14fc231..e55ed46 100644
--- a/Modules/ExternalProject.cmake
+++ b/Modules/ExternalProject.cmake
@@ -1079,7 +1079,7 @@ function(_ep_write_gitclone_script script_filename source_dir git_EXECUTABLE git
     message(FATAL_ERROR "Tag for git checkout should not be empty.")
   endif()
 
-  set(git_clone_options)
+  set(git_clone_options "--no-checkout")
   if(git_shallow)
     if(NOT GIT_VERSION_STRING VERSION_LESS 1.7.10)
       list(APPEND git_clone_options "--depth 1 --no-single-branch")
-- 
cgit v0.12