Update of B2EtaMuMu module
Add more eta(') final states by modifying existing line (StrippingB2EtaMuMuAllX0) and adding a new one (StrippingB2EtaMuMuEta2gg):
StrippingReport INFO Event 10000, Good event 10000
| *Decision name*|*Rate,%*|*Accepted*| *Mult*|*ms/evt*|
|_StrippingGlobal_ | 0.0400| 4| | 15.427|
|_StrippingSequenceStreamBhadron_ | 0.0400| 4| | 15.410|
|!StrippingB2EtaMuMuAllX0SelectionLine | 0.0100| 1| 1.000| 14.001|
|!StrippingB2EtaMuMuEta2ggSelectionLine | 0.0300| 3| 1.333| 0.130|
|!StrippingB2EtaMuMuAllX0SelectionLine_TIMING | 0.0100| 1| 1.000| 0.064|
|!StrippingB2EtaMuMuEta2ggSelectionLine_TIMING | 0.0300| 3| 1.333| 0.032|
This replaces merge request !1813 (closed).