restore folding logic from Travis or update error messages

[dirk-thomas]

See e.g.

rosdistro/test/rosdistro_check_urls_test.py

Lines 22 to 29 in a8d19c8

	with Fold() as fold:
	print("""Checking if the distribution files of '%s' contain valid urls for known hosting services.
	If this fails you can run 'scripts/check_rosdistro_urls.py file://`pwd`/%s %s' to perform the same check locally.
	""" % (distro_name, 'index.yaml', distro_name))
	if not check_rosdistro_urls(index_url, distro_name):
	failed_distros.append(distro_name)
	fold_blocks.append(fold.get_block_name())
	assert not failed_distros, "There were problems with urls in the distribution files for these distros: %s, see folded blocks above for details: %s" % (failed_distros, fold_blocks)

Regression from #24333.

[dirk-thomas]

@tfoote Friendly ping.

[tfoote]

This was discussed in the review on that as an acceptable regression with the improved performance. I'm not going to have time to look at it right now.

If someone has time to look at it . There looks like there's a group and ungroup is an alternative to folding:

• https://github.community/t/has-github-action-somthing-like-travis-fold/16841
• https://github.community/t/travis-fold-equivalent/18256
• https://github.com/actions/toolkit/blob/df7e2c13c89ea93069cad62f1adfe78a87111cc0/docs/commands.md#group-and-ungroup-log-lines