patch 8.2.1844: using "q" at the more prompt doesn't stop a long message

Problem:    Using "q" at the more prompt doesn't stop a long message.
Solution:   Check for "got_int". (closes #7122)

Author: brammool

src/message.c

@@ -1551,6 +1551,10 @@ msg_outtrans_len_attr(char_u *msgstr, int len, int attr)
     char_u	*s;
     int		mb_l;
     int		c;
+    int		save_got_int = got_int;
+
+    // Only quit when got_int was set in here.
+    got_int = FALSE;
 
     // if MSG_HIST flag set, add message to history
     if (attr & MSG_HIST)
@@ -1568,7 +1572,7 @@ msg_outtrans_len_attr(char_u *msgstr, int len, int attr)
      * Go over the string.  Special characters are translated and printed.
      * Normal characters are printed several at a time.
      */
-    while (--len >= 0)
+    while (--len >= 0 && !got_int)
     {
 	if (enc_utf8)
 	    // Don't include composing chars after the end.
@@ -1618,10 +1622,12 @@ msg_outtrans_len_attr(char_u *msgstr, int len, int attr)
 	}
     }
 
-    if (str > plain_start)
+    if (str > plain_start && !got_int)
 	// print the printable chars at the end
 	msg_puts_attr_len((char *)plain_start, (int)(str - plain_start), attr);
 
+    got_int |= save_got_int;
+
     return retval;
 }
 

src/testdir/dumps/Test_quit_long_message.dump

@@ -0,0 +1,6 @@
+> +0&#ffffff0@74
+|~+0#4040ff13&| @73
+|~| @73
+|~| @73
+|~| @73
+| +0#0000000&@56|0|,|0|-|1| @8|A|l@1| 

src/testdir/test_messages.vim

@@ -4,6 +4,7 @@ source check.vim
 source shared.vim
 source term_util.vim
 source view_util.vim
+source screendump.vim
 
 func Test_messages()
   let oldmore = &more
@@ -309,4 +310,20 @@ func Test_mapping_at_hit_return_prompt()
   nunmap <C-B>
 endfunc
 
+func Test_quit_long_message()
+  CheckScreendump
+
+  let content =<< trim END
+    echom range(9999)->join("\x01")
+  END
+  call writefile(content, 'Xtest_quit_message')
+  let buf = RunVimInTerminal('-S Xtest_quit_message', #{rows: 6})
+  call term_sendkeys(buf, "q")
+  call VerifyScreenDump(buf, 'Test_quit_long_message', {})
+
+  " clean up
+  call StopVimInTerminal(buf)
+  call delete('Xtest_diff_rnu')
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1844,
 /**/
     1843,
 /**/