check_dirty randomly failed

[gaul]

Seems racy. Logs:

---- check_dirty stdout ----
thread 'check_dirty' panicked at 'assertion failed: !xattr::get(&foo_cache, "user.catfs.src_chksum").unwrap().is_some()', tests/integration_tests.rs:393:13
stack backtrace:
   0: std::panicking::begin_panic
             at /rustc/7eac88abb2e57e752f3302f02be5f3ce3d7adfb4/library/std/src/panicking.rs:505
   1: integration_tests::check_dirty
             at ./tests/integration_tests.rs:393
   2: integration_tests::check_dirty::{{closure}}
             at ./tests/test_suite/mod.rs:6
   3: core::ops::function::FnOnce::call_once
             at /rustc/7eac88abb2e57e752f3302f02be5f3ce3d7adfb4/library/core/src/ops/function.rs:227
   4: core::ops::function::FnOnce::call_once
             at /rustc/7eac88abb2e57e752f3302f02be5f3ce3d7adfb4/library/core/src/ops/function.rs:227