bug#49240: Guix 1.3.0 tests/guix-environment.sh fails with Guile 2.2.7

[藍挺瑋]

The commit d613c1771a1986d3c0f1e034155fde41f32f9b8e seems to break tests/guix-
environment.sh test for Guix 1.3.0 on Guile 2.2.7.

The line which causes the test to fail is:

  (when (zero? (modulo (round (* 100. (/ transferred size))) 10))

When Guile 2.2.7 runs this line, it fails with the error:

  Wrong type (expecting exact integer): 2.0

The error comes from the call to 'zero?'.

This issue can be related to https://issues.guix.gnu.org/issue/44985 because the
commit mentioned above is an attempt to fix the issue.