The automatic completion of the gluster command is not compatible with grep version 3.8 or higher

[lv-mz]

When gluster is used together with grep version 3.8 or higher, pressing the Tab key for automatic completion will trigger a warning about egrep being deprecated ：
egrep: warning: egrep is obsolescent; using grep -E

and this waring message will print in commd lines ，like：
gluster peeregrep: warning: egrep is obsolescent; using grep -E egrep: warning: egrep is obsolescent; using grep -E

This is because, starting from grep 3.8, egrep was removed and replaced with grep -E. The relevant commit :
https://git.savannah.gnu.org/cgit/grep.git/commit/?id=a9515624709865d480e3142fd959bccd1c9372d1