egrep 3.8 warning four_ti_2.py tests

[dimpase]

egrep is getting obsolete, and emits a warning, affecting doctests in src/sage/interfaces/four_ti_2.py

$ egrep -V
egrep: warning: egrep is obsolescent; using /bin/grep -E
grep (GNU grep) 3.8
[...]

namely,

File "src/sage/interfaces/four_ti_2.py", line 370, in sage.interfaces.four_ti_2.FourTi2.rays
Failed example:
    four_ti_2.rays(four_ti_2._magic3x3())  # optional - 4ti2
Expected:
    [0 2 1 2 1 0 1 0 2]
    [1 0 2 2 1 0 0 2 1]
    [1 2 0 0 1 2 2 0 1]
    [2 0 1 0 1 2 1 2 0]
Got:
    egrep: warning: egrep is obsolescent; using /bin/grep -E
    egrep: warning: egrep is obsolescent; using /bin/grep -E
    egrep: warning: egrep is obsolescent; using /bin/grep -E
    egrep: warning: egrep is obsolescent; using /bin/grep -E
    egrep: warning: egrep is obsolescent; using /bin/grep -E
    [0 2 1 2 1 0 1 0 2]
    [1 0 2 2 1 0 0 2 1]
    [1 2 0 0 1 2 2 0 1]
    [2 0 1 0 1 2 1 2 0]
**********************************************************************
File "src/sage/interfaces/four_ti_2.py", line 458, in sage.interfaces.four_ti_2.FourTi2.circuits
Failed example:
    four_ti_2.circuits([1,2,3])  # optional - 4ti2
[...] # ditto

File "src/sage/interfaces/four_ti_2.py", line 496, in sage.interfaces.four_ti_2.FourTi2.groebner
Failed example:
    four_ti_2.groebner(A)  # optional - 4ti2
[...]

File "src/sage/interfaces/four_ti_2.py", line 499, in sage.interfaces.four_ti_2.FourTi2.groebner
Failed example:
    four_ti_2.groebner(lat=[[1,2,3],[1,1,1]])  # optional - 4ti2

Upstream issue: https://github.com/4ti2/4ti2/issues/37

Upstream: Reported upstream. No feedback yet.

CC: @mkoeppe

Component: packages: optional

Issue created by migration from https://trac.sagemath.org/ticket/34708

[mkoeppe]

Description changed:

--- 
+++ 
@@ -46,3 +46,5 @@

+Upstream issue: https://github.com/4ti2/4ti2/issues/37 +

[dimpase]

see https://github.com/4ti2/4ti2/pull/38

[dimpase]

by the way, there are egrep calls in Sage proper, too.