pull upstream changes from gitstatus

gitstatus/gitstatus.plugin.zsh

@@ -223,12 +223,15 @@ function gitstatus_start() {
       esac
     }
 
+    local -i sigwinch_pid=-1
+    (( ! ${GITSTATUS_SEND_SIGWINCH:-0} )) || sigwinch_pid=$$
+
     # We use `zsh -c` instead of plain {} or () to work around bugs in zplug. It hangs on startup.
     zsh -xc "
-      ${(q)daemon}             \
-        --lock-fd=3            \
-        --sigwinch-pid=$$      \
-        --num-threads=$threads \
+      ${(q)daemon}                   \
+        --lock-fd=3                  \
+        --sigwinch-pid=$sigwinch_pid \
+        --num-threads=$threads       \
         --dirty-max-index-size=$max_dirty
       echo -nE $'bye\x1f0\x1e'
     " <&$req_fd >&$resp_fd 2>$log_file 3<$lock_file &!