Fix bad parent_time_units for UKESM1-0-LL

[ledm]

Added a minor fix for UKESM1 cmip6 model. Literally, I just copied and pasted code from the HadGEM3 fix.

[valeriupredoi]

this should be solved by #231 so even though I am in favour of double-taking, I reckon we should wait for that PR to be merged and then see if there's any more issues 🍺

[valeriupredoi]

OK proves out we still need these type of fixes as @sloosvel pointed out, so @ledm pls fix the PEP hiccup and then it's good to go 🍺

[ledm]

Not sure about the codacy error, it looks like some of our standard behaviours for fixes are not PEP8 compliant.

[bouweandela]

Could you please add a unit test?

There have been some changes to how the fixes are setup in the last few months, could you please have a look at some other fixes and align this one? That should also solve the Codacy issues.

[bouweandela]

In fact, it looks like this work was already done by @schlunma last month:

ESMValCore/esmvalcore/cmor/_fixes/cmip6/ukesm1_0_ll.py

Lines 1 to 6 in a4ec54e

	"""Fixes for CMIP6 UKESM1-0-LL."""
	from .hadgem3_gc31_ll import AllVars as BaseAllVars
	class AllVars(BaseAllVars):
	"""Fixes for all vars."""

Can this be closed?

[bouweandela]

Suggested change

	except AttributeError:
	except KeyError:

AttributeError would be raised if cube.attributes did not exist, you probably mean KeyError, which would be raised if there is no key 'parent_time_units' in cube.attributes. Maybe it would be simpler to just write

if cube.attributes.get(parent_units, '') == bad_value:
    cube.attributes[parent_units] = 'days since 1850-01-01'

without the try except

[bouweandela]

@ledm Can you comment on this? #274 (comment) Is this still needed?

[schlunma]

I'm pretty sure this can be closed @ledm?

We got this in the current master:

ESMValCore/esmvalcore/cmor/_fixes/cmip6/ukesm1_0_ll.py

Lines 6 to 30 in fee5d54

	class AllVars(Fix):
	"""Fixes for all vars."""
	def fix_metadata(self, cubes):
	"""Fix parent time units.
	Parameters
	----------
	cubes : iris.cube.CubeList
	Input cubes.
	Returns
	-------
	iris.cube.CubeList
	"""
	parent_units = 'parent_time_units'
	bad_value = 'days since 1850-01-01-00-00-00'
	for cube in cubes:
	try:
	if cube.attributes[parent_units] == bad_value:
	cube.attributes[parent_units] = 'days since 1850-01-01'
	except AttributeError:
	pass
	return cubes

[schlunma]

Closing this (see comment above), feel free to reopen if necessary.