Does user agent matching match Google's spec?

[benjaminestes]

https://developers.google.com/search/reference/robots_txt#order-of-precedence-for-user-agents

Only one group is valid for a particular crawler. The crawler must determine the correct group of lines by finding the group with the most specific user-agent that still matches. All other groups are ignored by the crawler. The user-agent is case-sensitive. All non-matching text is ignored (for example, both googlebot/1.2 and googlebot* are equivalent to googlebot). The order of the groups within the robots.txt file is irrelevant.

[benjaminestes]

This bit here:

All non-matching text is ignored (for example, both googlebot/1.2 and googlebot* are equivalent to googlebot).

What this means is that user agents must essentially match the regular expression [a-zA-Z_-]+.
i.e googlebot/1.2 and googlebot* are nonconforming user agents and Google is choosing to handle them by discarding everything after the first invalid character.

I don't know off the top of my head whether the library is doing this.