misformatted cayley tables for matrix groups

[kcrisman]

G=SL(2,ZZ)
identity = matrix(ZZ, [[1,0], [0,1]])
G.cayley_table(names='elements',elements=[identity, -identity])

From ​this ask.sagemath.org question. Essentially, matrix groups don't seem to work out too well:

sage: G.cayley_table(names='elements',elements=[identity, -identity])
              *      [1 0]
[0 1] [-1  0]
[ 0 -1]
               +--------------------------------
    [1 0]
[0 1]|     [1 0]
[0 1] [-1  0]
[ 0 -1]
[-1  0]
[ 0 -1]| [-1  0]
[ 0 -1]     [1 0]
[0 1]

[jhpalmieri]

This is a duplicate of part of #10787. Can we close it?

[kcrisman]

Yes, certainly.