pull upstream changes from gitstatus

gitstatus/gitstatus.plugin.zsh

@@ -223,11 +223,14 @@ function gitstatus_start() {
       esac
     }
 
+    local -i sigwinch_pid=-1
+    (( ! ${GITSTATUS_SEND_SIGWINCH:-0} )) || sigwinch_pid=$$
+
     # We use `zsh -c` instead of plain {} or () to work around bugs in zplug. It hangs on startup.
     zsh -xc "
       ${(q)daemon}                   \
         --lock-fd=3                  \
-        --sigwinch-pid=$$      \
+        --sigwinch-pid=$sigwinch_pid \
         --num-threads=$threads       \
         --dirty-max-index-size=$max_dirty
       echo -nE $'bye\x1f0\x1e'