bug#13763: 23.4; emacs Info-tagify

[Glenn Morris]

Version: 24.4

mkiever@tlink.de wrote:

> ESC-: (info) RET
> ESC-: (Info-tagify) RET
>
> Debugger entered--Lisp error: (wrong-type-argument stringp nil)
>   file-name-nondirectory(nil)

OK; fixed (it's never worked).

> Another inconvenience because buffer-file-name is nil:
> Info-cease-edit asks for a filename now in save-buffer call.

It's always been like that. Seems a reasonable way for it to behave.