patch 8.2.3768: timer_info() has the wrong repeat value in a timer callback

Problem:    timer_info() has the wrong repeat value in a timer callback.
Solution:   Do not add one to the repeat value when in the callback.
            (closes #9294)
diff --git a/src/time.c b/src/time.c
index 362fd46..bb4a202 100644
--- a/src/time.c
+++ b/src/time.c
@@ -696,7 +696,8 @@
     dict_add_number(dict, "remaining", (long)remaining);
 
     dict_add_number(dict, "repeat",
-		    (long)(timer->tr_repeat < 0 ? -1 : timer->tr_repeat + 1));
+	    (long)(timer->tr_repeat < 0 ? -1
+			     : timer->tr_repeat + (timer->tr_firing ? 0 : 1)));
     dict_add_number(dict, "paused", (long)(timer->tr_paused));
 
     di = dictitem_alloc((char_u *)"callback");