tail: fix possible line loss and duplication when file is renamed

[elhimov]

tail: fix possible line loss and duplication when file is renamed

I didn't forget about (remove if it is not applicable):

• Well-written commit messages (see documentation how to write a commit message)
• Don't forget about TarantoolBot in a commit message (see example)
• Tests (see documentation for a testing package)
• Changelog (see documentation for changelog format)
• Documentation (see documentation for documentation style guide)

Related issues:

Closes TNTP-3131