Section 592: the population of events, after the predicate and the operand #3320

Recording the third defect class of the pass. The predicate is answered by unit tests; the operand by asking what the action reads (#3303, section 590); the population of EVENTS by nothing but enumeration.

Two defects it produced that every control missed: a push can be a deletion (#3309), and a commit can be a merge (#3319). Plus the two hazards met while measuring — git config in a worktree writes to the shared config, and a failed cd does not stop a subshell.