ScannerError ("could not found expected ':'") on reading map keys longer than 1024 characters

[ed.brannin@…]

I just got this error when reading a YAML map with a very long key:

    "could not found expected ':'", self.get_mark())
yaml.scanner.ScannerError: while scanning a simple key

If I delete the end of the key until it's 1024 characters long, it works.

(In this case, the keys in my map are SSH public keys for a Puppet manifest whose data I'm trying to export into YAML for easier editing.)

[ed.brannin@…]

Example YAML input that causes the issue

[ed.brannin@…]

PyYAML Test program that displays the issue

[ed.brannin@…]

I've attached a sample YAML file and Python script that demonstrate the issue. To see that key length is the issue, delete the end of THIS_IS_A_VERY_LONG_KEY from the start of "START_DELETING_HERE_".