pack-objects: document about thread synchronization

diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index c55ef099c3f174de10a29aaddfb750fa07aa2d8a..2b2181dca09089ed36d10ee8f6f67eedda8cf352 100644 (file)
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -294,8 +294,20 @@ write_script () {
 # The single parameter is the prerequisite tag (a simple word, in all
 # capital letters by convention).
 
+test_unset_prereq () {
+       ! test_have_prereq "$1" ||
+       satisfied_prereq="${satisfied_prereq% $1 *} ${satisfied_prereq#* $1 }"
+}
+
 test_set_prereq () {
-       satisfied_prereq="$satisfied_prereq$1 "
+       case "$1" in
+       !*)
+               test_unset_prereq "${1#!}"
+               ;;
+       *)
+               satisfied_prereq="$satisfied_prereq$1 "
+               ;;
+       esac
 }
 satisfied_prereq=" "
 lazily_testable_prereq= lazily_tested_prereq=