Auto merge of #3830 - ehuss:fix-squash-message, r=JohnTitor

Fix squash message warning.

rust-lang/rust#87671 added a warning when backslash continuations eat multiple lines. This uncovered that the message for squashing the index was missing some blank lines. This adds some newlines to silence the warning and fix the message formatting.

src/git.rs

@@ -398,11 +398,8 @@ pub fn squash_index(env: &Environment) -> Result<(), PerformError> {
     let now = Utc::now().format("%Y-%m-%d");
     let original_head = repo.head_oid()?.to_string();
     let msg = format!("Collapse index into one commit\n\n\
-
         Previous HEAD was {}, now on the `snapshot-{}` branch\n\n\
-
         More information about this change can be found [online] and on [this issue].\n\n\
-
         [online]: https://internals.rust-lang.org/t/cargos-crate-index-upcoming-squash-into-one-commit/8440\n\
         [this issue]: https://github.com/rust-lang/crates-io-cargo-teams/issues/47", original_head, now);