fix: several `HomotopyNonlinearFunction` fixes #610

Job	Run time
Tests (1, Downstream) / Tests - Downstream	45m 53s
Tests (1, Python) / Tests - Python	18m 36s
Tests (1, QA) / Tests - QA	11m 55s
Tests (1, Core) / Tests - Core	15m 36s
Tests (lts, Core) / Tests - Core	9m 23s
Tests (lts, Downstream) / Tests - Downstream	29m 38s
Tests (lts, Python) / Tests - Python	9m 30s
Tests (lts, QA) / Tests - QA	8m 35s
Tests (pre, Core) / Tests - Core	15m 33s
Tests (pre, Downstream) / Tests - Downstream	45m 17s
Tests (pre, Python) / Tests - Python	18m 53s
Tests (pre, QA) / Tests - QA	12m 3s
	4h 0m 52s

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