flaky test: should_keep_at_least_one_remaining_relearning_step

[cything]

This test fails during NixOS build CI. I was able to reproduce on my computer when running in a loop and it fails after 1.6k tries.

i=0; while BUILDHASH=87ccd24e CARGO=/nix/store/9113334r56fmi13i8j6k8r2x92ml3c6b-cargo-1.82.0/bin/.cargo-wrapped CARGO_MANIFEST_DIR=/home/yt/fun/anki/rslib CARGO_PKG_AUTHORS='Ankitects Pty Ltd and contributors <https://help.ankiweb.net>' CARGO_PKG_DESCRIPTION='Anki'\''s Rust library code' CARGO_PKG_HOMEPAGE='' CARGO_PKG_LICENSE=AGPL-3.0-or-later CARGO_PKG_LICENSE_FILE='' CARGO_PKG_NAME=anki CARGO_PKG_README=README.md CARGO_PKG_REPOSITORY='' CARGO_PKG_RUST_VERSION=1.80 CARGO_PKG_VERSION=0.0.0 CARGO_PKG_VERSION_MAJOR=0 CARGO_PKG_VERSION_MINOR=0 CARGO_PKG_VERSION_PATCH=0 CARGO_PKG_VERSION_PRE='' DESCRIPTORS_BIN=/home/yt/fun/anki/out/rslib/proto/descriptors.bin LD_LIBRARY_PATH='/home/yt/fun/anki/target/debug/build/blake3-361a3e4025b92fac/out:/home/yt/fun/anki/target/debug/build/libsqlite3-sys-2b9fac4fa100cdf3/out:/home/yt/fun/anki/target/debug/build/lzma-sys-4c92de5d2584e1df/out:/home/yt/fun/anki/target/debug/build/ring-04c75abcba01c79b/out:/home/yt/fun/anki/target/debug/build/ring-b6feb18defdb8367/out:/home/yt/fun/anki/target/debug/build/zstd-sys-731b2a2972018409/out:/home/yt/fun/anki/target/debug/deps:/home/yt/fun/anki/target/debug:/nix/store/wi84ms5hw85w3frljv2spmdl8768dw97-rustc-1.82.0/lib/rustlib/x86_64-unknown-linux-gnu/lib' MACOSX_DEPLOYMENT_TARGET=10.13.4 OUT_DIR=/home/yt/fun/anki/target/debug/build/anki-68ec7def58be565a/out PROTOC=/home/yt/fun/anki/out/extracted/protoc/bin/protoc PYO3_NO_PYTHON=1 STRINGS_PY=/home/yt/fun/anki/out/pylib/anki/_fluent.py STRINGS_TS=/home/yt/fun/anki/out/ts/lib/generated/ftl.ts /home/yt/fun/anki/target/debug/deps/anki-76c15a3e804e0d0c should_keep_at_least_one_remaining_relearning_step; do i=$((i+1)); done; echo $i

---- deckconfig::update::test::should_keep_at_least_one_remaining_relearning_step stdout ----
thread 'deckconfig::update::test::should_keep_at_least_one_remaining_relearning_step' panicked at rslib/src/scheduler/answering/mod.rs:557:61:
called `Result::unwrap()` on an `Err` value: InvalidInput { source: InvalidInputError { message: "bug: card modified without updating queue: id:1733598406997 card:1733598407 entry:1733598406", source: None, backtrace: None } }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace


failures:
    deckconfig::update::test::should_keep_at_least_one_remaining_relearning_step

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 293 filtered out; finished in 0.01s

1631 # this many tries

Similar issue: #3353

[abdnh]

Can reproduce