patch 8.2.3946: when an internal error makes Vim exit the error is not seen

Problem:    When an internal error makes Vim exit the error is not seen.
Solution:   Add the error to the test output.
diff --git a/src/message.c b/src/message.c
index 7e98d0b..8768065 100644
--- a/src/message.c
+++ b/src/message.c
@@ -824,10 +824,13 @@
 iemsg(char *s)
 {
     if (!emsg_not_now())
+    {
 	emsg_core((char_u *)s);
 #ifdef ABORT_ON_INTERNAL_ERROR
-    abort();
+	set_vim_var_string(VV_ERRMSG, (char_u *)s, -1);
+	abort();
 #endif
+    }
 }
 
 #ifndef PROTO  // manual proto with __attribute__
diff --git a/src/testdir/runtest.vim b/src/testdir/runtest.vim
index 912bc20..d4c42f3 100644
--- a/src/testdir/runtest.vim
+++ b/src/testdir/runtest.vim
@@ -304,6 +304,7 @@
 func EarlyExit(test)
   " It's OK for the test we use to test the quit detection.
   if a:test != 'Test_zz_quit_detected()'
+    call add(v:errors, v:errmsg)
     call add(v:errors, 'Test caused Vim to exit: ' . a:test)
   endif
 
diff --git a/src/version.c b/src/version.c
index a04c91c..25e40bf 100644
--- a/src/version.c
+++ b/src/version.c
@@ -750,6 +750,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3946,
+/**/
     3945,
 /**/
     3944,