Hey #Drupal 8 #D8 #Composer friends, I'm having a weird composer issue:

Admin pages suddenly crash, seemingly out of the blue:

```
UnexpectedValueException: Invalid version string "main" in Composer\Semver\VersionParser->normalize()
```

It seems like Drupal is trying to see if there are core updates (>= 8.9.20), and then receives a "main" version identifier that composer can't deal with?

Possibly related to the new "main" branching scheme in D11 pushed 2 hours ago?