Incorrect lastModified value

[edolstra]

Describe the bug

I observed this random failure in the flake regression test suite:

diff --git a/tests/acaloiaro/di-tui/0.1.85+rev-12ae555a00205926da7cb5216d7f070e57b7508e/contents.json b/tests/acaloiaro/di-tui/0.1.85+rev-12ae555a00205926da7cb5216d7f070e57b7508e/contents-new.json
index 478c4e8..81b18d3 100644
--- a/tests/acaloiaro/di-tui/0.1.85+rev-12ae555a00205926da7cb5216d7f070e57b7508e/contents.json
+++ b/tests/acaloiaro/di-tui/0.1.85+rev-12ae555a00205926da7cb5216d7f070e57b7508e/contents-new.json
@@ -1 +1 @@
 {"docs":{"devShells":"The `devShells` flake output contains derivations that provide a build environment for `nix develop`.\n","packages":"The `packages` flake output contains packages that can be added to a shell using `nix shell`.\n"},"inventory":{"devShells":{"children":{"aarch64-darwin":{"children":{"default":{"derivation":"/nix/store/1br0kf1jymr6hfymmsnql1nw09qiw9cf-nix-shell.drv","forSystems":["aarch64-darwin"],"outputs":{"out":"/nix/store/p5dgb83nm1q1vrsds85gk7l4vvfa93g0-nix-shell"},"shortDescription":"","what":"development environment"}}},"aarch64-linux":{"children":{"default":{"derivation":"/nix/store/lrhq97gbihryj828fyf77aji4g44iyj9-nix-shell.drv","forSystems":["aarch64-linux"],"outputs":{"out":"/nix/store/xk0yxvlzkar69ipnksl215zsl94a1598-nix-shell"},"shortDescription":"","what":"development environment"}}},"x86_64-darwin":{"children":{"default":{"derivation":"/nix/store/1yplmrjp3976qg1aw5bc0km3sfa7qf56-nix-shell.drv","forSystems":["x86_64-darwin"],"outputs":{"out":"/nix/store/y8p6an9pwqbdvvln32gazpk8gj5bx37w-nix-shell"},"shortDescription":"","what":"development environment"}}},"x86_64-linux":{"children":{"default":{"derivation":"/nix/store/7wbzj4rf0hbjx9i3maxn6x8161afmyj5-nix-shell.drv","forSystems":["x86_64-linux"],"outputs":{"out":"/nix/store/n8k7k154h8pcr8zygw773ddy1m7506bp-nix-shell"},"shortDescription":"","what":"development environment"}}}}},"packages":{"children":{"aarch64-darwin":{"children":{"default":{"derivation":"
-/nix/store/5nxrgmw3s2rq3r3rpkrg5g8sga6sa5hh-di-tui-19700101.drv
+/nix/store/1pdn1icf5xv9afmdarx5rvaj6kbfd550-di-tui-20230915.drv
 ","forSystems":["aarch64-darwin"],"outputs":{"out":"
-/nix/store/z6gx1fpm6ckrqjc8ahr50hr8i5balgh4-di-tui-19700101
+/nix/store/gxzqxpwnwn97ijwfp9vi7yhzh3yilylr-di-tui-20230915
 "},"shortDescription":"","what":"package"}}},"aarch64-linux":{"children":{"default":{"derivation":"
-/nix/store/znqkcfw9cliq5vymfv831bdyw2jdsrps-di-tui-19700101.drv
+/nix/store/w0v14fhvb1xwwvvfr0qyhvsbggxshn0i-di-tui-20230915.drv
 ","forSystems":["aarch64-linux"],"outputs":{"out":"
-/nix/store/qdx3m7cqah8r6l28b7i9lj33sh8w2nnd-di-tui-19700101
+/nix/store/6yjc58p6nw3ljsj06fdjhflnz4pr4b71-di-tui-20230915
 "},"shortDescription":"","what":"package"}}},"x86_64-darwin":{"children":{"default":{"derivation":"
-/nix/store/hgg0i7pn588d4cbhvj19j2b3mz2lm6ad-di-tui-19700101.drv
+/nix/store/64g3dmkbxl4als9xwvrb8ym4qbsfdsln-di-tui-20230915.drv
 ","forSystems":["x86_64-darwin"],"outputs":{"out":"
-/nix/store/1qcdm8a8xgimi06d8swpqp2cffa1wn70-di-tui-19700101
+/nix/store/b0aziipy3c6j0dyiw8a7my4xa5wl6h9v-di-tui-20230915
 "},"shortDescription":"","what":"package"}}},"x86_64-linux":{"children":{"default":{"derivation":"
-/nix/store/izp8wbyfpd4h05fk9k6agskahlk9bixg-di-tui-19700101.drv
+/nix/store/q9r0xx4lwklaws7m1j6a9whmzypf558h-di-tui-20230915.drv
 ","forSystems":["x86_64-linux"],"outputs":{"out":"
-/nix/store/sg8pf2mi34m372ydfii7qjmwbqanxnrz-di-tui-19700101
+/nix/store/paqqrhbjdwn0wgk7xs5pcxd7sazrh3r2-di-tui-20230915
 "},"shortDescription":"","what":"package"}}}}}},"version":1}
~
❌ tests/acaloiaro/di-tui/0.1.85+rev-12ae555a00205926da7cb5216d7f070e57b7508e

The diff suggests that the lastModified value of the flake input isn't always passed correctly.

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Expected behavior

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nix-env --version output

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