remove cleaning PS1 before init

[LuckySB]

OS: Centos7
pkg: bash-completion-2.1-8.el7.noarch.rpm

/etc/profile.d/bash_completion.sh

# Check for interactive bash and that we haven't already been sourced.
[ -z "$BASH_VERSION" -o -z "$PS1" -o -n "$BASH_COMPLETION_COMPAT_DIR" ] && return

so, when PS1="" - no source /usr/share/bash-completion/bash_completion
and type -t _get_comp_words_by_ref return empty string
autocomplete not working