'cargo install -f syncer' fails with 'conflicting implementations of trait std::convert::From<&_> ...'

[happybeing]

Both

cargo install -f syncer

and

cargo install -f --debug syncer 

Give the following error but cargo update && cargo build and cargo build --release both succeed.

  Compiling blake2 v0.7.1
   Compiling rusqlite v0.13.0
error[E0119]: conflicting implementations of trait `std::convert::From<&_>` for type `types::to_sql::ToSqlOutput<'_>`:
  --> /home/mrh/.cargo/registry/src/github.com-1ecc6299db9ec823/rusqlite-0.13.0/src/types/to_sql.rs:26:1
   |
18 | / impl<'a, T: ?Sized> From<&'a T> for ToSqlOutput<'a>
19 | |     where &'a T: Into<ValueRef<'a>>
20 | | {
21 | |     fn from(t: &'a T) -> Self {
22 | |         ToSqlOutput::Borrowed(t.into())
23 | |     }
24 | | }
   | |_- first implementation here
25 | 
26 |   impl<'a, T: Into<Value>> From<T> for ToSqlOutput<'a> {
   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `types::to_sql::ToSqlOutput<'_>`
   |
   = note: downstream crates may implement trait `std::convert::From<&_>` for type `types::value::Value`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0119`.
error: could not compile `rusqlite`.

To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
error: failed to compile `syncer v0.5.1`, intermediate artifacts can be found at `/tmp/cargo-installmEHbMA`

Caused by:
  build failed

[happybeing]

Above is with a clone of master on Ubuntu 19.04 using Rustc v1.44.0, Cargo v1.44.0.

[happybeing]

Update: I found Cargo issue rust-lang/cargo#7169 and so tried:

git checkout Cargo.lock # which ensures I'm up to date with your master
cargo install -f --locked syncer

But still get the same error. I'm not fluent in Cargo or Rustc so don't understand what the difference might be between cargo build and cargo install.

[happybeing]

Workaround

I'm not sure why cargo install -f --locked syncer fails or why cargo update && cargo build can succeed (since that presumably gets latest package versions?).

However, using cargo install --path . works, so the following appears to be ok:

cargo update && cargo build && cargo install --path .

Haven't tried running syncer yet though! 😄

I'll leave this open as the README instructions may not work currently as they suggest cargo install -f syncer