Timestamp serialization does not use the canonical representation

[stefan6419846]

When doing some analysis regarding timestamps and how they are rendered by pyyaml, we stumbled upon the fact that

pyyaml/lib/yaml/representer.py

Lines 219 to 221 in 69c141a

	def represent_datetime(self, data):
	value = data.isoformat(' ')
	return self.represent_scalar('tag:yaml.org,2002:timestamp', value)

would always use the space-separated variant instead of the canonical way described in https://yaml.org/type/timestamp.html This broke some tests, as other tools like django-rest-framework and its serializers would use the canonical variant.

Digging through the code, this apparently has always been like this in pyyaml: cc316a4#diff-13bed56fc23472d5ca7cd84fd0428c0d64f18f68591c1c48fbf686c1c253aa1aR192

From the specification, I would have expected the regular ISO8601 variant to be the default:

This can be serialized using a subset of the ISO8601 format and the formats proposed by the W3C note on datetime. In addition, a more relaxed format is also supported for enhanced readability, using white space separation.

For now, we are working around this with a custom dumper, but I would expect the reference library to follow its own specification, especially going the canonical way.