Use get_eval for check_required computation

issue3473
review1561002
(transplanted from 4786286136344caf3e4bda27c23ac1ab911d9380)

--HG--
extra : transplant_source : G%86%28a64L%AF%3EK%DA%27%C2%3A%C1%AB%91%1D%93%80
Send None for missing parent records instead of False

issue3448
review1761002
(transplanted from 207e9ee40735a5f9a37b796807f5f56189d25dba)

--HG--
extra : transplant_source : %20%7E%9E%E4%075%A5%F9%A3%7Byh%07%F5%F5a%89%D2%5D%BA