revision: make get_commit_action() a pure predicate #29079

Job	Run time
config	9s
fuzz smoke test	1m 18s
win build	2m 31s
osx-gcc (macos-14)	2m 31s
win+Meson build	2m 31s
sparse	1m 55s
osx-reftable (macos-14)	2m 31s
osx-meson (macos-14)	2m 31s
rust-analysis	2m 31s
osx-clang (macos-14)	2m 31s
static-analysis	2m 31s
documentation	2m 31s
win+VS build	0s
almalinux-8 (almalinux:8)	2m 31s
linux-reftable-leaks (ubuntu:rolling)	2m 31s
linux-TEST-vars (ubuntu:20.04)	2m 31s
linux-breaking-changes (ubuntu:rolling)	2m 31s
linux-sha256 (ubuntu:rolling)	2m 31s
linux32 (i386/ubuntu:20.04)	2m 31s
linux-reftable (ubuntu:rolling)	2m 30s
linux-musl-meson (alpine:latest)	2m 30s
fedora-breaking-changes-meson (fedora:latest)	2m 30s
linux-meson (ubuntu:rolling)	2m 30s
linux-asan-ubsan (ubuntu:rolling)	2m 30s
linux-leaks (ubuntu:rolling)	2m 30s
win+VS test	-1s
debian-11 (debian:11)	2m 30s
win test	0s
win+Meson test	0s
	58m 36s

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