Re: [PATCH v2] column: show auto columns when pager is active

> When columns are set to automatic for git tag and the output is
> paginated by git, the output is a single column instead of multiple
> columns.
>
> Standard behaviour in git is to honor auto values when the pager is
> active, which happens for example with commands like git log showing
> colors when being paged.
>
> Since ff1e72483 (tag: change default of `pager.tag` to "on",
> 2017-08-02), the pager has been enabled by default, exposing this
> problem to more people.
>
> finalize_colopts in column.c only checks whether the output is a TTY to
> determine if columns should be enabled with columns set to auto. Also
> check if the pager is active.
>
> Adding a test for git column is possible but requires some care to work
> around a race on stdin. See commit 18d8c2693 (test_terminal: redirect
> child process' stdin to a pty, 2015-08-04). Test git tag instead, since
> that does not involve stdin, and since that was the original motivation
> for this patch.

> +test_expect_success TTY 'git tag with auto-columns ' '
> +	test_commit one &&
> +	test_commit two &&
> +	test_commit three &&
> +	test_commit four &&
> +	test_commit five &&
> +	cat >expected <<\EOF &&
> +initial  one      two      three    four     five
> +EOF
> +	test_terminal env PAGER="cat >actual.tag" COLUMNS=80 \
> +		git -c column.ui=auto tag --sort=authordate &&
> +	test_cmp expected actual.tag
> +'