zsh completion doesn't work with sudo

[sim590]

• I have read through the manual page (man fzf). But that doesn't apply anyway...
• I have the latest version of fzf
• I have searched through the existing issues

Info

• OS
  • GNU/Linux
  • Mac OS X
  • Windows
  • Etc.
• Shell
  • bash
  • zsh
  • fish

Problem / Steps to reproduce

Zsh completion for custom programs doesn't work when sudo is the first word on the command line. Usual completion with zsh does support that behaviour on the other hand, i.e. completion for some program name foo will work even though sudo is the first word on the command line.

However, this is not limited to custom definitions. The case of kill doesn't work. For instance, writing

$ kill **<TAB>

works, but the following doesn't:

$ sudo kill **<TAB>

[yyy33]

The same goes for my bash

[junegunn]

Related #1992 #2130