3 consecutive blocks created for a single tx

[mdyring]

Describe the bug
Submitting a single tx results in 3 consecutive blocks created.

How to reproduce
Submit tx on v0.5.5

Expected behavior
2 blocks: one containing the tx and one for finalisation.

Screenshots or log output

Jan 19 13:03:56 i-0f6670abb7a863172 emd[1647]: I[2020-01-19|13:03:56.874] Executed block                               module=state height=10 validTxs=1 invalidTxs=0
Jan 19 13:03:56 i-0f6670abb7a863172 emd[1647]: I[2020-01-19|13:03:56.876] Committed state                              module=state height=10 txs=1 appHash=6D2FF0A609BD0AEE312ACFD282FF7FA3C6647F6396F397DA9044CA92C0501C8B
Jan 19 13:03:57 i-0f6670abb7a863172 emd[1647]: I[2020-01-19|13:03:57.381] Executed block                               module=state height=11 validTxs=0 invalidTxs=0
Jan 19 13:03:57 i-0f6670abb7a863172 emd[1647]: I[2020-01-19|13:03:57.383] Committed state                              module=state height=11 txs=0 appHash=9B833C0F3E03BD4E7F4917B8E8409713822B6DB87389FBE78DBB7E324FD877C4
Jan 19 13:03:57 i-0f6670abb7a863172 emd[1647]: I[2020-01-19|13:03:57.890] Executed block                               module=state height=12 validTxs=0 invalidTxs=0
Jan 19 13:03:57 i-0f6670abb7a863172 emd[1647]: I[2020-01-19|13:03:57.892] Committed state                              module=state height=12 txs=0 appHash=9B833C0F3E03BD4E7F4917B8E8409713822B6DB87389FBE78DBB7E324FD877C4

Additional context
Related to changes in inflation gating?