Cargo-coverage will blow up if cargo build wasn't ran once

[roblabla]

How to reproduce:

roblabla@roblab ~/tmp $ cargo new meh
     Created library `meh` project
roblabla@roblab ~/tmp $ cd meh/
roblabla@roblab ~/tmp/meh $ cargo coverage

Trace:

roblabla@roblab ~/tmp/meh $ env RUST_BACKTRACE=1 cargo coverage
Downloading kcov
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" }', libcore/result.rs:945:5
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::_print
             at libstd/sys_common/backtrace.rs:71
   2: std::panicking::default_hook::{{closure}}
             at libstd/sys_common/backtrace.rs:59
             at libstd/panicking.rs:207
   3: std::panicking::default_hook
             at libstd/panicking.rs:223
   4: std::panicking::rust_panic_with_hook
             at libstd/panicking.rs:402
   5: std::panicking::begin_panic_fmt
             at libstd/panicking.rs:349
   6: rust_begin_unwind
             at libstd/panicking.rs:325
   7: core::panicking::panic_fmt
             at libcore/panicking.rs:72
   8: core::result::unwrap_failed
             at /checkout/src/libcore/macros.rs:26
   9: <core::result::Result<T, E>>::unwrap
             at /checkout/src/libcore/result.rs:782
  10: cargo_travis::build_kcov
             at /home/roblabla/.cargo/registry/src/github.com-1ecc6299db9ec823/cargo-travis-0.0.9/src/lib.rs:141
  11: cargo_coverage::execute
             at src/bin/cargo-coverage.rs:107
  12: cargo::call_main_without_stdin
             at /home/roblabla/.cargo/registry/src/github.com-1ecc6299db9ec823/cargo-0.22.0/src/cargo/lib.rs:128
  13: cargo_coverage::main::{{closure}}
             at src/bin/cargo-coverage.rs:194
  14: cargo_coverage::main
             at src/bin/cargo-coverage.rs:185
  15: std::rt::lang_start::{{closure}}
             at /checkout/src/libstd/rt.rs:74
  16: std::panicking::try::do_call
             at libstd/rt.rs:59
             at libstd/panicking.rs:306
  17: __rust_maybe_catch_panic
             at libpanic_unwind/lib.rs:102
  18: std::rt::lang_start_internal
             at libstd/panicking.rs:285
             at libstd/panic.rs:361
             at libstd/rt.rs:58
  19: std::rt::lang_start
             at /checkout/src/libstd/rt.rs:74
  20: main
  21: __libc_start_main
  22: _start

[JP-Ellis]

Cargo coverage also fails if $CARGO_TARGET_DIR is anything else than the default as the ./target directory need not exist. For example, I have CARGO_TARGET_DIR=$HOME/.cache/cargo.