Add work around to RichPID unpacking to correct incorrect data version.

Cherry-picked from 2018-patches merge request !1245 (merged)

@jonrob FYI

Looks good, thanks.

• [2018-04-18 00:11] Validation started with lhcb-clang-test#924
• [2018-04-18 00:12] Validation started with lhcb-gaudi-head-py3#127
• [2018-04-18 00:12] Validation started with lhcb-head#1822
• [2018-04-18 00:14] Validation started with lhcb-tdr-test#123
• [2018-04-18 00:16] Validation started with lhcb-gaudi-head#1839
• [2018-04-18 19:09] Validation started with lhcb-gaudi-merge#490
• [2018-04-19 00:10] Validation started with lhcb-lcg-dev3#499
• [2018-04-19 00:11] Validation started with lhcb-clang-test#925
• [2018-04-19 00:12] Validation started with lhcb-lcg-dev4#499
• [2018-04-19 00:12] Validation started with lhcb-gaudi-head-py3#128
• [2018-04-19 00:12] Validation started with lhcb-tdr-test#124
• [2018-04-19 00:14] Validation started with lhcb-head#1823
• [2018-04-19 00:14] Validation started with lhcb-gaudi-head#1840
• [2018-04-19 08:19] Validation started with lhcb-gaudi-merge#491

merged

mentioned in commit 9ba21676

mentioned in merge request Brunel!390 (merged)

mentioned in merge request !1245 (merged)