bug#33881: 27.0.50; flymake-show-diagnostics-buffer throwing 'Selecting deleted buffer' error

[John Shahid]

I was able to fix the issue by applying the following patch

>From 2dda8ad72bb5a1603473d9420e90e8d1d694a134 Mon Sep 17 00:00:00 2001
From: John Shahid <jvshahid@gmail.com>
Date: Wed, 26 Dec 2018 16:45:33 -0500
Subject: [PATCH] Always set the source buffer before reverting

* lisp/progmodes/flymake.el (flymake-show-diagnostics-buffer): Do it.
---
 lisp/progmodes/flymake.el | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lisp/progmodes/flymake.el b/lisp/progmodes/flymake.el
index 7b100da42b..c773eb1c15 100644
--- a/lisp/progmodes/flymake.el
+++ b/lisp/progmodes/flymake.el
@@ -1332,9 +1332,9 @@ flymake-show-diagnostics-buffer
          (target (or (get-buffer name)
                      (with-current-buffer (get-buffer-create name)
                        (flymake-diagnostics-buffer-mode)
-                       (setq flymake--diagnostics-buffer-source source)
                        (current-buffer)))))
     (with-current-buffer target
+      (setq flymake--diagnostics-buffer-source source)
       (revert-buffer)
       (display-buffer (current-buffer)))))
 
-- 
2.19.2