for-each-repo: work correctly in a worktree #26613

Job	Run time
config	6s
fuzz smoke test	1m 25s
win+Meson build	6m 12s
static-analysis	5m 17s
sparse	22m 35s
win build	4m 45s
rust-analysis	1m 53s
osx-clang (macos-14)	24m 48s
osx-gcc (macos-14)	19m 6s
osx-meson (macos-14)	23m 44s
documentation	7m 42s
osx-reftable (macos-14)	30m 14s
win+VS build	0s
linux-reftable-leaks (ubuntu:rolling)	31m 14s
fedora-breaking-changes-meson (fedora:latest)	9m 55s
linux-sha256 (ubuntu:rolling)	13m 32s
linux-breaking-changes (ubuntu:rolling)	10m 34s
linux-musl-meson (alpine:latest)	7m 7s
almalinux-8 (almalinux:8)	10m 39s
linux-meson (ubuntu:rolling)	12m 23s
linux32 (i386/ubuntu:focal)	10m 44s
linux-leaks (ubuntu:rolling)	29m 4s
linux-TEST-vars (ubuntu:20.04)	13m 49s
linux-reftable (ubuntu:rolling)	13m 59s
debian-11 (debian:11)	10m 17s
linux-asan-ubsan (ubuntu:rolling)	36m 37s
win+VS test	-1s
win+Meson test (6)	35s
win+Meson test (1)	36s
win+Meson test (5)	30s
win+Meson test (7)	34s
win+Meson test (9)	45s
win+Meson test (8)	37s
win+Meson test (3)	43s
win+Meson test (4)	46s
win+Meson test (0)	36s
win+Meson test (2)	36s
win test (3)	8m 2s
win test (5)	7m 12s
win test (9)	10m 22s
win test (4)	8m 57s
win test (6)	6m 44s
win test (1)	46s
win test (2)	9m 14s
win test (7)	6m 36s
win test (0)	9m 32s
win test (8)	5m 50s
	7h 17m 13s

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