Run git-daemon indirectly again but check for instances

tests/helpers.sh

@@ -60,15 +60,17 @@ function small-repo-in-sandbox() {
 }
 
 function launch-git-daemon() {
-    local port=9418 exec_path
+    local port=9418
     if nc -z localhost "$port"; then
       echo "Port $port should not have been open before this test's run of the git daemon!" >&2
       return 1
     fi
-    exec_path="$(git --exec-path)"
-    # TODO: Maybe dynamically set the `GIT_CONFIG_*` vars, to accommodate preexisting ones.
-    GIT_CONFIG_COUNT=1 GIT_CONFIG_KEY_0=uploadpack.allowRefInWant GIT_CONFIG_VALUE_0=true \
-      "$exec_path/git-daemon" --verbose --base-path=. --export-all --user-path &>/dev/null &
+    if pgrep git-daemon; then
+      # TODO: This may be over-broad, as we only need port 9418 (on whatever of 127.0.0.1 and ::1 exist).
+      echo 'An instance of git-daemon seems to be running already!' >&2
+      return 1
+    fi
+    git -c uploadpack.allowRefInWant=true daemon --verbose --base-path=. --export-all --user-path &>/dev/null &
     daemon_pid=$!
     while ! nc -z localhost "$port"; do
       sleep 0.1