Riviera fails to compile OSVVM 2021.09

[crdavis12]

Starting with VUnit 4.6.0 I get an error when compiling OSVVM with Riviera (2020.10 and 2019.04):

COMP96 WARNING COMP96_0048: "This function may complete without return statement." "/home/domain/crdavis/virtualenv/msry_env/lib/python3.7/site-packages/vunit/vhdl/osvvm/ScoreboardPkg_slv_c.vhd" 1795 5
COMP96 WARNING COMP96_0048: "This function may complete without return statement." "/home/domain/crdavis/virtualenv/msry_env/lib/python3.7/site-packages/vunit/vhdl/osvvm/ScoreboardPkg_slv_c.vhd" 2225 5
COMP96 ERROR COMP96_0106: "Returned value type does not match the type declared in function declaration." "/home/domain/crdavis/virtualenv/msry_env/lib/python3.7/site-packages/vunit/vhdl/osvvm/ScoreboardPkg_slv_c.vhd" 2619 12
COMP96 ERROR COMP96_0106: "Returned value type does not match the type declared in function declaration." "/home/domain/crdavis/virtualenv/msry_env/lib/python3.7/site-packages/vunit/vhdl/osvvm/ScoreboardPkg_slv_c.vhd" 2627 12
COMP96 Compile failure 2 Errors 2 Warnings  Analysis time :  30.0 [ms]

It looks like this is a non-generic package included for compatability with Cadence. OSVVM has the following in their build script:

if {$::osvvm::ToolVendor ne "Cadence"}  {
  analyze ScoreboardGenericPkg.vhd
  analyze ScoreboardPkg_slv.vhd
  analyze ScoreboardPkg_int.vhd
} else {
  analyze ScoreboardPkg_slv_c.vhd
  analyze ScoreboardPkg_int_c.vhd
}

Which makes me think something similar is needed in builtins._add_osvvm