Fix two bugs with `split_file_to_collection` #1533

Job	Run time
Setup cache and determine changed repositories (3.7)	5m 41s
Lint tool-list (3.7)	45s
Check file sizes	20s
Lint Python scripts (3.7)	23s
Lint R scripts (ubuntu-20.04, release)	3m 56s
Test tools (0, 3.7)	6m 34s
Combine chunked test results (3.7)	29s
Check workflow success	1s
Deploy	0s
Report deploy status	0s
	18m 9s

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