Files
Michael Daniels fb16e1d195 tests.replaceVars: fix group mismatches
This fixes group mismatches observed on Darwin, e.g.:

```
replaceVars-succeeds
--- /nix/store/wahj58fiii5j1jy6s9mpbdyxzhq3plnb-source.txt
+++ /nix/store/bfmykrc9r5ycy0dj8l1z2p9c5116dny8-expected
├── stat {}
│ @@ -1,7 +1,7 @@
│
│    Size: 96        	Blocks: 0          IO Block: 4096   directory
│ -Device: 1,15	Access: (0555/dr-xr-xr-x)  Uid: (    0/    root)   Gid: (    0/   wheel)
│ +Device: 1,15	Access: (0555/dr-xr-xr-x)  Uid: (    0/    root)   Gid: (  350/  nixbld)
│
│  Modify: 1970-01-01 00:00:01.000000000 +0000
```

(cherry picked from commit 3a5c240ffe)
2026-06-20 20:48:47 +00:00
..
…
2025-09-13 06:11:14 -07:00
…
2025-07-24 13:55:40 +02:00
2025-11-10 10:41:31 -08:00
2025-11-10 10:41:31 -08:00