Re: [PATCH] test-lib.sh: set COLUMNS=80 for --verbose repeatability

> Some tests will fail under --verbose because while we've unset COLUMNS
> since b1d645b58ac (tests: unset COLUMNS inherited from environment,
> 2012-03-27), we also look for the columns with an ioctl(..,
> TIOCGWINSZ, ...) on some platforms. By setting COLUMNS again we
> preempt the TIOCGWINSZ lookup in pager.c's term_columns(), it'll take
> COLUMNS over TIOCGWINSZ,
> 
> This fixes the t0500-progress-display.sh test when run as:
> 
>     ./t0500-progress-display.sh --verbose
> 
> It broke because of a combination of the this issue and the progress
> output reacting to the column width since 545dc345ebd (progress: break
> too long progress bar lines, 2019-04-12). The
> t5324-split-commit-graph.sh fails in a similar manner due to progress
> output, see [1] for details.
> 
> A more narrow fix here would be to only do this in the --verbose mode,
> but there's no harm in setting this for everything. If we're not
> connected to a TTY the COLUMNS setting won't matter.