Git commit search hides commits until 4th char (BB-10965)

I am searching for a specific commit: 2891771

On the commit page I enter data into the commit search box (hint: "Find commits")

When I enter 3 first chars: 289

• Actual result: is a list of two commits where the Message includes the number 289, but not the commit with id 2891771
• Expected result: the commit with id 2891771 should also show up in result-list

When I enter the 4th character, so that the search is for: 2891

• Result includes the commit, as expected. (Well actually, only the commit is included)