vim-patch:8.0.0607 (#6879)

Problem:    When creating a bufref, then using :bwipe and :new it might get
            the same memory and bufref_valid() returns true.
Solution:   Add br_fnum to check the buffer number didn't change.

45e5fd135d

src/nvim/quickfix.c

@@ -191,7 +191,7 @@ typedef struct {
 // Looking up a buffer can be slow if there are many.  Remember the last one
 // to make this a lot faster if there are multiple matches in the same file.
 static char_u *qf_last_bufname = NULL;
-static bufref_T  qf_last_bufref = { NULL, 0 };
+static bufref_T  qf_last_bufref = { NULL, 0, 0 };
 
 /*
  * Read the errorfile "efile" into memory, line by line, building the error
@@ -2330,9 +2330,7 @@ void qf_history(exarg_T *eap)
   }
 }
 
-/*
- * Free error list "idx".
- */
+/// Free all the entries in the error list "idx".
 static void qf_free(qf_info_T *qi, int idx)
 {
   qfline_T    *qfp;