vim-patch:9.1.0565: Stop directory doesn't work properly in 'tags'

Problem:  Stop directory doesn't work properly in 'tags'.
          (Jesse Pavel)
Solution: Also move the stop directory forward by one byte.
          (zeertzjq)

This doesn't support relative stop directories yet, as they are not
supported in other places like findfile() either.

fixes: vim/vim#15200
related: vim/vim#15202

68819afb2c

src/nvim/tag.c

@@ -2583,6 +2583,10 @@ int get_tagfname(tagname_T *tnp, int first, char *buf)
       // move the filename one char forward and truncate the
       // filepath with a NUL
       filename = path_tail(buf);
+      if (r_ptr != NULL) {
+        STRMOVE(r_ptr + 1, r_ptr);
+        r_ptr++;
+      }
       STRMOVE(filename + 1, filename);
       *filename++ = NUL;