Cherry-pick MR !198 to 2018-patches branch

Execute legacy behaviour in Tesla only for legacy data types

See merge request !198 (merged)

(cherry picked from commit bea25013)

b01d0f7f Execute legacy behaviour only for legacy data types.

• [2018-05-03 00:29] Validation started with lhcb-moore-test#45
• [2018-05-03 00:30] Validation started with lhcb-run2-patches#3
• [2018-05-03 00:31] Validation started with lhcb-2018-patches#201
• [2018-05-03 01:26] Validation started with lhcb-2018-patches#201

merged

mentioned in commit 60d876e1