patch, 2 partst: fixes for Perl-less tests

> In 6aec8d38fdd (t: refactor tests depending on Perl to print data,
> 2025-04-03) we have changed some of the tests in t4150 to use sed(1)
> instead of Perl. One of the conversions is broken though:
>
>     sed: -e expression #1, char 41: unterminated `s' command
>
> Curiously enough, the test itself still passes. This is caused by a
> sequence of failures:
>
>   1. The output of sed(1) is piped into git-update-ref(1), and because
>      sed(1) is the upstream command we don't notice that it fails.
>
>   2. git-update-ref(1) does not receive any input and thus won't create
>      any references.
>
>   3. We then repack the repository with the configured pseudo merges
>      pattern, but as we didn't create any references the pattern doesn't
>      match anything.
>
>   4. We use `test_pseudo_merges()` to compute the list of pseudo-merges
>      and write it into a file. This file is empty as there are none.
>
>   5. The loop over the pseudo-merges becomes a no-op.
>
>   6. The final test succeeds as well because the number of lines in an
>      empty file is obviously the same as the number of unique lines,
>      namely zero.
>
> Fix the issue by adding the terminating '|' to the sed(1) command.

> Reported-by: SZEDER Gábor <szeder.dev@gmail.com>
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  t/t5333-pseudo-merge-bitmaps.sh | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/t/t5333-pseudo-merge-bitmaps.sh b/t/t5333-pseudo-merge-bitmaps.sh
> index ba5ae6a00c9..1f7a5d82ee4 100755
> --- a/t/t5333-pseudo-merge-bitmaps.sh
> +++ b/t/t5333-pseudo-merge-bitmaps.sh
> @@ -234,8 +234,8 @@ test_expect_success 'pseudo-merge pattern with capture groups' '
>  			test_commit_bulk 16 &&
>  
>  			git rev-list HEAD~16.. >in &&
> -			sed "s|\(.*\)|create refs/remotes/$r/tags/\1 \1" in |
> -			git update-ref --stdin || return 1
> +			sed "s|\(.*\)|create refs/remotes/$r/tags/\1 \1|" in >refs &&
> +			git update-ref --stdin <refs || return 1
>  		done &&
>  
>  		git \

> Patrick Steinhardt <ps@pks.im> writes:
> 
> > In 6aec8d38fdd (t: refactor tests depending on Perl to print data,
> > 2025-04-03) we have changed some of the tests in t4150 to use sed(1)
> > instead of Perl. One of the conversions is broken though:
> >
> >     sed: -e expression #1, char 41: unterminated `s' command
> >
> > Curiously enough, the test itself still passes. This is caused by a
> > sequence of failures:
> >
> >   1. The output of sed(1) is piped into git-update-ref(1), and because
> >      sed(1) is the upstream command we don't notice that it fails.
> >
> >   2. git-update-ref(1) does not receive any input and thus won't create
> >      any references.
> >
> >   3. We then repack the repository with the configured pseudo merges
> >      pattern, but as we didn't create any references the pattern doesn't
> >      match anything.
> >
> >   4. We use `test_pseudo_merges()` to compute the list of pseudo-merges
> >      and write it into a file. This file is empty as there are none.
> >
> >   5. The loop over the pseudo-merges becomes a no-op.
> >
> >   6. The final test succeeds as well because the number of lines in an
> >      empty file is obviously the same as the number of unique lines,
> >      namely zero.
> >
> > Fix the issue by adding the terminating '|' to the sed(1) command.
> 
> OK.
> 
> > Furthermore, make the test a tiny bit more robust by not using it as
> > part of a pipe.
> 
> While I do not think it would give us big enough improvement to
> revert this part of the change, I would have liked not to see this
> "furthermore" change.  We are not in the business of catching
> segfault in 'sed' that is supplied by the platform, so there is no
> point in breaking the pipeline here.
> 
> Will queue.  Thanks.