test-lib.sh - cygwin does not have usable FIFOs

Do not use FIFOs on cygwin, they do not work. Cygwin includes
coreutils, so has mkfifo, and that command does something. However,
the resultant named pipe is known (on the Cygwin mailing list at
least) to not work correctly.

This disables PIPE for Cygwin, allowing t0008.sh to complete (all other
tests in that file work correctly).
Signed-off-by: NMark Levedahl <mlevedahl@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

t/test-lib.sh

@@ -737,7 +737,14 @@ test_i18ngrep () {
 
 test_lazy_prereq PIPE '
 	# test whether the filesystem supports FIFOs
+	case $(uname -s) in
+	CYGWIN*)
+		false
+		;;
+	*)
 		rm -f testfifo && mkfifo testfifo
+		;;
+	esac
 '
 
 test_lazy_prereq SYMLINKS '