Backward compatible interface of IAlgorithm for GaudiPython

Fixes a problem similar to #75 (closed) (hidden by #75 (closed) itself).

changed milestone to %v32r2

added bug fix label

• [2019-09-26 14:42] Validation started with lhcb-gaudi-merge#828
• [2019-09-27 00:03] Validation started with lhcb-gaudi-head-py3#191
• [2019-09-27 00:03] Validation started with lhcb-lcg-dev4#1043
• [2019-09-27 00:03] Validation started with lhcb-lcg-dev3#1033
• [2019-09-27 00:04] Validation started with lhcb-sanitizers#383
• [2019-09-27 00:04] Validation started with lhcb-test-throughput2#164
• [2019-09-27 00:07] Validation started with lhcb-tdr-test#686
• [2019-09-27 00:09] Validation started with lhcb-gaudi-head#2399
• [2019-09-27 00:09] Validation started with lhcb-run2-patches-dev4#91
• [2019-09-27 09:11] Validation started with lhcb-run2-patches-dev4#92
• [2019-09-27 13:03] Validation started with lhcb-lcg-dev4#1044

approved this merge request

merged

mentioned in commit c292550f