bash-completions: egrep => `grep -E`

Typing in a terminal emulator `kdevelop -s`, then pressing Tab prints
the following warning:
    egrep: warning: egrep is obsolescent; using grep -E

The two commands are equivalent, at least on Manjaro:
    $ cat /usr/bin/egrep
    cmd=${0##*/}
    echo "$cmd: warning: $cmd is obsolescent; using grep -E" >&2
    exec grep -E "$@"