Sync with 2.22.2

* maint-2.22: (43 commits)
  Git 2.22.2
  Git 2.21.1
  mingw: sh arguments need quoting in more circumstances
  mingw: fix quoting of empty arguments for `sh`
  mingw: use MSYS2 quoting even when spawning shell scripts
  mingw: detect when MSYS2's sh is to be spawned more robustly
  t7415: drop v2.20.x-specific work-around
  Git 2.20.2
  t7415: adjust test for dubiously-nested submodule gitdirs for v2.20.x
  Git 2.19.3
  Git 2.18.2
  Git 2.17.3
  Git 2.16.6
  test-drop-caches: use `has_dos_drive_prefix()`
  Git 2.15.4
  Git 2.14.6
  mingw: handle `subst`-ed "DOS drives"
  mingw: refuse to access paths with trailing spaces or periods
  mingw: refuse to access paths with illegal characters
  unpack-trees: let merged_entry() pass through do_add_entry()'s errors
  ...

1 files changed, 7 insertions, 4 deletions

diff --git a/t/helper/test-drop-caches.c b/t/helper/test-drop-caches.c
index f65e301f9d..7b4278462b 100644
--- a/t/helper/test-drop-caches.c
+++ b/t/helper/test-drop-caches.c
@@ -8,18 +8,21 @@ static int cmd_sync(void)
 {
 	char Buffer[MAX_PATH];
 	DWORD dwRet;
-	char szVolumeAccessPath[] = "\\\\.\\X:";
+	char szVolumeAccessPath[] = "\\\\.\\XXXX:";
 	HANDLE hVolWrite;
-	int success = 0;
+	int success = 0, dos_drive_prefix;
 
 	dwRet = GetCurrentDirectory(MAX_PATH, Buffer);
 	if ((0 == dwRet) || (dwRet > MAX_PATH))
 		return error("Error getting current directory");
 
-	if (!has_dos_drive_prefix(Buffer))
+	dos_drive_prefix = has_dos_drive_prefix(Buffer);
+	if (!dos_drive_prefix)
 		return error("'%s': invalid drive letter", Buffer);
 
-	szVolumeAccessPath[4] = Buffer[0];
+	memcpy(szVolumeAccessPath, Buffer, dos_drive_prefix);
+	szVolumeAccessPath[dos_drive_prefix] = '\0';
+
 	hVolWrite = CreateFile(szVolumeAccessPath, GENERIC_READ | GENERIC_WRITE,
 		FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);
 	if (INVALID_HANDLE_VALUE == hVolWrite)