test: rename $satisfied to $satisfied_prereq

All other shell variables that are used to globally keep track of
states related to prerequisite have "prereq" somewhere in their
names.  Be consistent and avoid potential name crashes with other
kinds of satisfaction in the future.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/test-lib-functions.sh

@@ -221,9 +221,9 @@ write_script () {
 # capital letters by convention).
 
 test_set_prereq () {
-	satisfied="$satisfied$1 "
+	satisfied_prereq="$satisfied_prereq$1 "
 }
-satisfied=" "
+satisfied_prereq=" "
 
 test_have_prereq () {
 	# prerequisites can be concatenated with ','
@@ -239,7 +239,7 @@ test_have_prereq () {
 	for prerequisite
 	do
 		total_prereq=$(($total_prereq + 1))
-		case $satisfied in
+		case "$satisfied_prereq" in
 		*" $prerequisite "*)
 			ok_prereq=$(($ok_prereq + 1))
 			;;