patch 8.1.0242: Insert mode completion may use an invalid buffer pointer

Problem:    Insert mode completion may use an invalid buffer pointer.
Solution:   Check for ins_buf to be valid. (closes #3290)

Author: brammool

src/edit.c

@@ -4419,10 +4419,15 @@ ins_compl_get_exp(pos_T *ini)
 					    ? (char_u *)"." : curbuf->b_p_cpt;
 	last_match_pos = first_match_pos = *ini;
     }
+    else if (ins_buf != curbuf && !buf_valid(ins_buf))
+	ins_buf = curbuf;  // In case the buffer was wiped out.
 
     compl_old_match = compl_curr_match;	/* remember the last current match */
     pos = (compl_direction == FORWARD) ? &last_match_pos : &first_match_pos;
-    /* For ^N/^P loop over all the flags/windows/buffers in 'complete' */
+
+    /*
+     * For ^N/^P loop over all the flags/windows/buffers in 'complete'.
+     */
     for (;;)
     {
 	found_new_match = FAIL;

src/version.c

@@ -794,6 +794,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    242,
 /**/
     241,
 /**/