for-each-repo: work correctly in a worktree #26701

Job	Run time
config	6s
fuzz smoke test	1m 5s
win+Meson build	5m 55s
win+VS build	-1s
win build	4m 59s
static-analysis	5m 22s
rust-analysis	1m 29s
documentation	6m 38s
sparse	3m 24s
osx-gcc (macos-14)	6m 22s
osx-reftable (macos-14)	6m 17s
linux-reftable (ubuntu:rolling)	6m 27s
linux-leaks (ubuntu:rolling)	6m 26s
linux-reftable-leaks (ubuntu:rolling)	6m 28s
osx-meson (macos-14)	5m 32s
linux32 (i386/ubuntu:focal)	6m 27s
linux-meson (ubuntu:rolling)	6m 26s
linux-sha256 (ubuntu:rolling)	6m 27s
linux-TEST-vars (ubuntu:20.04)	6m 27s
fedora-breaking-changes-meson (fedora:latest)	6m 26s
linux-musl-meson (alpine:latest)	6m 26s
linux-breaking-changes (ubuntu:rolling)	4m 54s
linux-asan-ubsan (ubuntu:rolling)	6m 27s
almalinux-8 (almalinux:8)	6m 26s
debian-11 (debian:11)	1m 26s
osx-clang (macos-14)	3m 24s
win+VS test	0s
win test (6)	6m 39s
win test (7)	6m 15s
win test (1)	6m 49s
win test (2)	9m 59s
win test (5)	6m 37s
win test (3)	5m 55s
win test (4)	10m 46s
win test (9)	10m 44s
win test (8)	6m 43s
win test (0)	6m 28s
win+Meson test (1)	9m 8s
win+Meson test (2)	12m 18s
win+Meson test (5)	11m 7s
win+Meson test (9)	6m 11s
win+Meson test (3)	10m 43s
win+Meson test (7)	9m 32s
win+Meson test (8)	7m 36s
win+Meson test (6)	6m 45s
win+Meson test (0)	6m 37s
win+Meson test (4)	9m 23s
	4h 54m 0s

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