Allow for no log files to be compressed

[blimlim]

The implementation of model log compression in #532 has a bug which causes OM2 runs to fail.

Compression is currently run from the cice.py driver, using the get_log_files() and compress_log_files() methods. The get_log_files_method() searches the work directory for files matching regex patterns contained in the model.logs_to_compress list.

For example in cice.py we set:

payu/payu/models/cice.py

Lines 58 to 61 in 0c2a837

	self.logs_to_compress = [r"iceout[0-9]{3}",
	r"debug\.root\.[0-9]{2}",
	r"ice_diag\.d",
	r"ice_diag_out"]

which matches all the desired log files for CICE4 in ESM1.5.

While for cice5.py we set:

payu/payu/models/cice5.py

Lines 45 to 46 in 0c2a837

	# Empty list means no log files will be compressed
	self.logs_to_compress = []

The intended behaviour is for no files to be compressed when model.logs_to_compress is empty.

In the actual implementation, the opposite happens when model.logs_to_compress is empty:

payu/payu/models/cice.py

Lines 335 to 339 in 0c2a837

	log_files = []
	for filename in os.listdir(self.work_path):
	if re.match("|".join(self.logs_to_compress), filename):
	log_files.append(os.path.join(self.work_path, filename))
	return log_files

The "|".join(self.logs_to_compress) statement produces "", which then matches every file in the model's work directory. model.compress_log_files() then tries to compress and delete everything.

In OM2, this causes the following error.

Traceback (most recent call last):
  File "/g/data/vk83/prerelease/apps/payu/dev/bin/payu-run", line 8, in <module>
    sys.exit(runscript())
  File "/g/data/vk83/prerelease/apps/payu/dev/lib/python3.10/site-packages/payu/subcommands/run_cmd.py", line 135, in runscript
    expt.archive(force_prune_restarts=run_args.force_prune_restarts)
  File "/g/data/vk83/prerelease/apps/payu/dev/lib/python3.10/site-packages/payu/experiment.py", line 799, in archive
    model.archive()
  File "/g/data/vk83/prerelease/apps/payu/dev/lib/python3.10/site-packages/payu/models/cice.py", line 324, in archive
    self.compress_log_files()
  File "/g/data/vk83/prerelease/apps/payu/dev/lib/python3.10/site-packages/payu/models/cice.py", line 353, in compress_log_files
    os.remove(file)
IsADirectoryError: [Errno 21] Is a directory: '/scratch/tm70/sw6175/access-om2/work/cice-resdate-changes-test-release-025deg_jra55_ryf-bc5b6712/ice/OUTPUT'