Load group->parent_group when loading from restart file

opm/io/eclipse/rst/group.hpp

@@ -32,6 +32,7 @@ struct RstHeader;
 
 struct RstGroup {
     RstGroup(const UnitSystem& unit_system,
+             const RstHeader& header,
              const std::string* zwel,
              const int * igrp,
              const float * sgrp,

opm/io/eclipse/rst/header.hpp

@@ -86,6 +86,7 @@ struct RstHeader {
     int ntfreg;
     int nplmix;
     int ngroup;
+    int nwgmax;
 
     bool e300_radial;
     bool e100_radial;

src/opm/io/eclipse/rst/group.cpp

@@ -33,12 +33,13 @@ namespace RestartIO {
 using M  = ::Opm::UnitSystem::measure;
 
 RstGroup::RstGroup(const ::Opm::UnitSystem& unit_system,
+                   const RstHeader& header,
                    const std::string* zwel,
                    const int * igrp,
                    const float * sgrp,
                    const double * xgrp) :
     name(trim_copy(zwel[0])),
-    parent_group(igrp[VI::IGroup::ParentGroup] ),
+    parent_group(igrp[header.nwgmax + VI::IGroup::ParentGroup] ),
     oil_rate_limit(                unit_system.to_si(M::liquid_surface_rate,   sgrp[VI::SGroup::OilRateLimit])),
     water_rate_limit(              unit_system.to_si(M::liquid_surface_rate,   sgrp[VI::SGroup::WatRateLimit])),
     gas_rate_limit(                unit_system.to_si(M::gas_surface_rate,      sgrp[VI::SGroup::GasRateLimit])),

src/opm/io/eclipse/rst/header.cpp

@@ -84,6 +84,7 @@ RstHeader::RstHeader(const std::vector<int>& intehead, const std::vector<bool>&
     ntfip(intehead[VI::intehead::NTFIP]),
     nmfipr(intehead[VI::intehead::NMFIPR]),
     ngroup(intehead[VI::intehead::NGRP]),
+    nwgmax(intehead[VI::intehead::NWGMAX]),
     //
     e300_radial(logihead[VI::logihead::E300Radial]),
     e100_radial(logihead[VI::logihead::E100Radial]),

src/opm/io/eclipse/rst/state.cpp

@@ -181,6 +181,7 @@ void RstState::add_groups(const std::vector<std::string>& zgrp,
         std::size_t xgrp_offset = ig * this->header.nxgrpz;
 
         this->groups.emplace_back(this->unit_system,
+                                  this->header,
                                   zgrp.data() + zgrp_offset,
                                   igrp.data() + igrp_offset,
                                   sgrp.data() + sgrp_offset,

tests/test_rst.cpp

@@ -247,6 +247,7 @@ BOOST_AUTO_TEST_CASE(group_test) {
         std::size_t xgrp_offset = ig * header.nxgrpz;
 
         Opm::RestartIO::RstGroup group(unit_system,
+                                       header,
                                        zgrp.data() + zgrp_offset,
                                        igrp.data() + igrp_offset,
                                        sgrp.data() + sgrp_offset,