Point to latest v5.1.2_cherry commit.
Point to latest v5.1.2_cherry commit.

A fix for a flaky test has been merged and squashed: https://github.com/crate/elasticsearch/pull/122

crate/crate,crate/crate,EvilMcJerkface/crate,EvilMcJerkface/crate,EvilMcJerkface/crate,crate/crate