can't find crates about cargo-udeps HOT 6 CLOSED

Loading save analysis from "/home/matthias/vcs/github/cargo/target/debug/deps/save-analysis/libcrates_io-728b49bbdee2d583.json"
thread 'main' panicked at 'could not find "curl"', /home/matthias/.cargo/git/checkouts/cargo-udeps-a54b3ec58ed788c4/fd3cedf/src/main.rs:402:24
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.35/src/backtrace/libunwind.rs:88
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.35/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:47
   3: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:36
   4: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:200
   5: std::panicking::default_hook
             at src/libstd/panicking.rs:214
   6: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:477
   7: std::panicking::continue_panic_fmt
             at src/libstd/panicking.rs:384
   8: std::panicking::begin_panic_fmt
             at src/libstd/panicking.rs:339
   9: cargo_udeps::main::{{closure}}
  10: cargo_udeps::main
  11: std::rt::lang_start::{{closure}}
  12: std::rt::lang_start_internal::{{closure}}
             at src/libstd/rt.rs:49
  13: std::panicking::try::do_call
             at src/libstd/panicking.rs:296
  14: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:80
  15: std::panicking::try
             at src/libstd/panicking.rs:275
  16: std::panic::catch_unwind
             at src/libstd/panic.rs:394
  17: std::rt::lang_start_internal
             at src/libstd/rt.rs:48
  18: main
  19: __libc_start_main
  20: _start
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.