Fails on files containing only git file moves

[sourcefrog]

Split from sourcefrog/cargo-mutants#580:

This file fails to parse in 5131c5d:

diff --git a/tests/test-utils/Cargo.toml b/test-utils/Cargo.toml
similarity index 100%
rename from tests/test-utils/Cargo.toml
rename to test-utils/Cargo.toml
diff --git a/tests/test-utils/src/io.rs b/test-utils/src/io.rs
similarity index 100%
rename from tests/test-utils/src/io.rs
rename to test-utils/src/io.rs
diff --git a/tests/test-utils/src/lib.rs b/test-utils/src/lib.rs
similarity index 100%
rename from tests/test-utils/src/lib.rs
rename to test-utils/src/lib.rs
diff --git a/tests/test-utils/src/read.rs b/test-utils/src/read.rs
similarity index 100%
rename from tests/test-utils/src/read.rs
rename to test-utils/src/read.rs
diff --git a/tests/test-utils/src/write.rs b/test-utils/src/write.rs
similarity index 100%
rename from tests/test-utils/src/write.rs
rename to test-utils/src/write.rs