Fix pack threads definition in GC script

Change-Id: I04b5aab5637c3287b25a385a10b00dae2b1ee432
diff --git a/maintenance/git-gc/scripts/utils.sh b/maintenance/git-gc/scripts/utils.sh
index 1213c7e..63e64e6 100755
--- a/maintenance/git-gc/scripts/utils.sh
+++ b/maintenance/git-gc/scripts/utils.sh
@@ -65,7 +65,7 @@
 
     [ -z "$PRUNE_PACK_EXPIRE" ] || $GIT config gc.prunePackExpire $PRUNE_PACK_EXPIRE
     [ -z "$PRUNE_EXPIRE" ] || $GIT config gc.pruneExpire $PRUNE_EXPIRE
-    [ -z "$PACK_THREADS" ] || $GIT config gc.packThreads $PACK_THREADS
+    [ -z "$PACK_THREADS" ] || $GIT config pack.threads $PACK_THREADS
 
     JAVA_ARGS="$JAVA_ARGS -Xmx$(java_heap_for_repo)k"
     log_project "$proj" "Running java_args=\"$JAVA_ARGS\" $JGIT gc $GIT_GC_OPTION ..."