Summary: Ref T1191. Similar issue to D10613. This column usually has a hash exactly 12 bytes long, but sometimes stores an internal builtin query name like "open", "all", etc. It might be nice to promote those to 12-byte hashes of a consistent length eventually, but for now just make this a variable-length column.
Test Plan: Ran migration, no longer saw issues with reordering builtin saved searches.
Reviewers: btrahan
Subscribers: epriestley
Maniphest Tasks: T1191
Differential Revision: https://secure.phabricator.com/D10614
epriestley
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