`cargo watch` stuck in infinite loop

[upbqdn]

cargo watch is stuck in an infinite loop. The culprit seems to be

librustzcash/zcash_client_memory/build.rs

Lines 43 to 44 in 2b80d78

	// Copy the generated types into the source tree so changes can be committed.
	fs::copy(out.join("memwallet.rs"), "src/proto/memwallet.rs")?;