macos Catalina, failed to build librsvg

[jjl75]

:info:build error[E0506]: cannot assign to self.input.cached_token because it is borrowed :info:build --> /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_graphics_librsvg/librsvg/work/librsvg-2.44.14/vendor/cssparser/src/parser.rs:572:17 :info:build | :info:build 547 | pub fn next_including_whitespace_and_comments(&mut self) -> Result<&Token<'i>, BasicParseError<'i>> { :info:build | - let's call the lifetime of this reference '1 :info:build ... :info:build 560 | Some(ref cached_token) :info:build | ---------------- borrow of self.input.cached_token occurs here :info:build ... :info:build 572 | self.input.cached_token = Some(CachedToken { :info:build | ^{assignment to borrowed self.input.cached_token occurs here :info:build ... :info:build 584 | Ok(token) :info:build | --------- returning this value requires that self.input.cached_token.0 is borrowed for '1 :info:build error: aborting due to previous error :info:build For more information about this error, try rustc --explain E0506. :info:build error: Could not compile cssparser. :info:build Caused by: :info:build process didn't exit successfully: `rustc --crate-name cssparser ...}