geckodriver @0.21.0: error[E0713]: borrow may still be in use when destructor runs

[ryandesign (Ryan Carsten Schmidt)]

geckodriver @0.21.0 does not build, at least not on my High Sierra system:

error[E0713]: borrow may still be in use when destructor runs
   --> /opt/local/var/macports/build/_Users_rschmidt_macports_macports-ports-ryandesign-fork_www_geckodriver/geckodriver/work/.home/.cargo/macports/url-1.7.0/src/form_urlencoded.rs:261:40
    |
259 | impl<'a> Target for ::UrlQuery<'a> {
    |      -- lifetime `'a` defined here
260 |     fn as_mut_string(&mut self) -> &mut String { &mut self.url.serialization }
261 |     fn finish(self) -> &'a mut ::Url { self.url }
    |                                        ^^^^^^^^ - here, drop of `self` needs exclusive access to `*self.url`, because the type `UrlQuery<'_>` implements the `Drop` trait
    |                                        |
    |                                        returning this value requires that `*self.url` is borrowed for `'a`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0713`.
error: could not compile `url`.
Caused by:
  process didn't exit successfully: `rustc --crate-name url /opt/local/var/macports/build/_Users_rschmidt_macports_macports-ports-ryandesign-fork_www_geckodriver/geckodriver/work/.home/.cargo/macports/url-1.7.0/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts --crate-type lib --emit=dep-info,metadata,link -C opt-level=3 -C metadata=c96cba656cf5527c -C extra-filename=-c96cba656cf5527c --out-dir /opt/local/var/macports/build/_Users_rschmidt_macports_macports-ports-ryandesign-fork_www_geckodriver/geckodriver/work/mozilla-geckodriver-96cf6b3/target/x86_64-apple-darwin/release/deps --target x86_64-apple-darwin -L dependency=/opt/local/var/macports/build/_Users_rschmidt_macports_macports-ports-ryandesign-fork_www_geckodriver/geckodriver/work/mozilla-geckodriver-96cf6b3/target/x86_64-apple-darwin/release/deps -L dependency=/opt/local/var/macports/build/_Users_rschmidt_macports_macports-ports-ryandesign-fork_www_geckodriver/geckodriver/work/mozilla-geckodriver-96cf6b3/target/release/deps --extern idna=/opt/local/var/macports/build/_Users_rschmidt_macports_macports-ports-ryandesign-fork_www_geckodriver/geckodriver/work/mozilla-geckodriver-96cf6b3/target/x86_64-apple-darwin/release/deps/libidna-2d5f648cea3861f9.rmeta --extern matches=/opt/local/var/macports/build/_Users_rschmidt_macports_macports-ports-ryandesign-fork_www_geckodriver/geckodriver/work/mozilla-geckodriver-96cf6b3/target/x86_64-apple-darwin/release/deps/libmatches-1840480986f9e3ab.rmeta --extern percent_encoding=/opt/local/var/macports/build/_Users_rschmidt_macports_macports-ports-ryandesign-fork_www_geckodriver/geckodriver/work/mozilla-geckodriver-96cf6b3/target/x86_64-apple-darwin/release/deps/libpercent_encoding-1a47c06c7f21da60.rmeta --cap-lints allow -C linker=/usr/bin/clang` (exit code: 1)
warning: build failed, waiting for other jobs to finish...
error: build failed
Command failed:  cd "/opt/local/var/macports/build/_Users_rschmidt_macports_macports-ports-ryandesign-fork_www_geckodriver/geckodriver/work/geckodriver-0.21.0" && /opt/local/bin/cargo build --release --frozen -v -j8
Exit code: 101