Global database configuration is ignored when advisories are locally configured

[Nemo157]

> cat $CARGO_HOME/audit.toml
# smh cargo-audit, get your own dirs, stop borrowing cargo's
[database]
path = "/home/nemo157/.cache/cargo-audit/advisory-db"
fetch = false
stale = false

> cat .cargo/audit.toml
[advisories]
ignore = [
    "RUSTSEC-2020-0036", # failure is officially deprecated/unmaintained
    # https://github.com/rust-lang/docs.rs/issues/1014

    "RUSTSEC-2023-0018", # rustwide -> remove_dir_all,TOCTOU / Race Condition
    # https://github.com/rust-lang/docs.rs/issues/2074
]
informational_warnings = ["unmaintained"] # warn for categories of informational advisories
severity_threshold = "low" # CVSS severity ("none", "low", "medium", "high", "critical")

[output]
quiet = false
deny = ["unmaintained"] # yanked is allowed for now

> cargo audit
    Fetching advisory database from `https://github.com/RustSec/advisory-db.git`
error: couldn't fetch advisory database: git operation failed: failed to make directory '/run/user/1000/cargo-home/advisory-db': Permission denied; class=Os (2)

> rm .cargo/audit.toml

> cargo audit
    Fetching advisory database from `https://github.com/RustSec/advisory-db.git`
      Loaded 580 security advisories (from /home/nemo157/.cache/cargo-audit/advisory-db)
...

> cargo audit --version
cargo-audit 0.17.6

Also reproduced with cargo-audit 0.18.2, the error message is just about not being able to acquire the lock instead.

(For context: I have a read-only $CARGO_HOME with all of Cargo's directories linked out to more "correct" locations, I am now trying to get all the third-party tools that have been dumping their files in there to also use the directories they should have been).