I get a strange error on shards master. Using this dependency:

dependencies:
  shards:
    github: crystal-lang/shards
    commit: "5666481"

$ shards install
Resolving dependencies
Fetching https://github.com/crystal-lang/shards.git
Unable to satisfy the following requirements:

- `shards (commit 5666481)` required by `shard.yml`
Failed to resolve dependencies

The shards binary is built from current master Shards 0.10.0 [ee74934] (2020-05-06).

5666481 is definitely a valid commit on this repo, so I see no reason why this should fail.

The latest release build (Shards 0.10.0 [4091ac5] (2020-04-06)) works as expected.