The left/right operands produced when `verbose > 1` should not contain newlines, because they are used to
build the `summary` string. The `assertrepr_compare` function returns a list of lines, and the summary is one of those lines and should not contain newlines itself.
Fix#9742
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Bruno Oliveira <nicoddemus@gmail.com>
Samuel Colvin