InEpsilon has inconsistent results with expected or actual values of Inf

[brackendawson]

func TestInEpsilon1(t *testing.T) {
	div := 0.0
	require.InEpsilon(t, 1, 1/div, 0.001)
}

func TestInEpsilon2(t *testing.T) {
	div := 0.0
	require.InEpsilon(t, 1/div, 1, 0.001)
}

> go test -v -run InEps | grep -E '(PASS|FAIL)'
--- FAIL: TestInEpsilon1 (0.00s)
--- PASS: TestInEpsilon2 (0.00s)

Originally posted by @ybrustin-te in #918 (comment)

Given the difference between two Inf values cannot be determined, those assertions should both fail.