Kcov not working with Rust binaries

Anyone else having difficulties running kcov on rust binaries recently? I used to be able to use kcov with my rust libraries to generate code coverage with Travis CI which would upload them to Coveralls. Within the past two months or so, every time I try to generate code coverage for my projects I get only one line of coverage, even in projects where I haven't changed the code or the config file, just reran the Travis build. For example, https://github.com/jeromefroe/clock_cache