Passa lock fails due to KeyError

[frostming]

Run passa lock on the add_test_frost branch.

Traceback (most recent call last):
  File "C:\Users\frostming\.virtualenvs\passa-ZPGQzv6O\Scripts\passa-script.py", line 11, in <module>
    load_entry_point('passa', 'console_scripts', 'passa')()
  File "d:\workspace\passa\src\passa\cli\__init__.py", line 47, in main
    result = f(options)
  File "d:\workspace\passa\src\passa\cli\lock.py", line 14, in run
    return lock(project=options.project)
  File "d:\workspace\passa\src\passa\actions\lock.py", line 12, in lock
    success = lock(locker)
  File "d:\workspace\passa\src\passa\operations\lock.py", line 13, in lock
    locker.lock()
  File "d:\workspace\passa\src\passa\models\lockers.py", line 158, in lock
    provider.collected_requires_pythons,
  File "d:\workspace\passa\src\passa\models\metadata.py", line 210, in set_metadata
    dependencies, pythons, copy.deepcopy(traces),
  File "d:\workspace\passa\src\passa\models\metadata.py", line 161, in _calculate_metasets_mapping
    dependencies, pythons, key, trace, all_metasets,
  File "d:\workspace\passa\src\passa\models\metadata.py", line 140, in _build_metasets
    python = pythons[key]
KeyError: 'plette[validation]'

[frostming]

passa/src/passa/internals/utils.py

Lines 141 to 148 in 8024741

	def strip_extras(requirement):
	# type: (Requirement) -> Requirement
	"""Returns a new requirement object with extras removed.
	"""
	line = requirement.as_line()
	new = type(requirement).from_line(line)
	new.extras = None
	return new

This is because Requirement.from_line() hits the LRU cache and didn't create a new instance, which results in unexpectedly stripping the extras from the original requirement.