Combination of --toolchain=openxc7 and --no-compile-gateware options

[Mecrisp]

I am trying to generate the example design using the openXC7 toolchain for a Kintex-7 based Genesys2 for which the toolchain option to the litex-boards target file has been kindly added (see litex-hub/litex-boards#624).

I installed the openXC7 toolchain using the nix toolchain installer, https://github.com/openXC7/toolchain-nix which resides in a different environment than LiteX, and it seems as if the --no-compile-gateware is ignored when specifying the --toolchain=openxc7 option.

~/FPGA/LiteX/litex-boards/litex_boards/targets/digilent_genesys2.py --toolchain=openxc7 --output-dir=genesys2-nogates --build --no-compile-gateware

/snap/openxc7/current/opt/nextpnr-xilinx/external/prjxray-db/ does not exist on your system. 
Do you have the openXC7 toolchain installed? 
You can get it here: https://github.com/openXC7/toolchain-installer

On the other hand, trying to run LiteX from within the nix environment entered using nix develop github:openxc7/toolchain-nix results in invisible/missing tools for running LiteX.

I would like the ability to first generate a script in LiteX for later synthesis of the gateware without dependencies on nextpnr-xilinx at this stage, and then switching to the openXC7 environment to actually run the synthesis script in its own environment, just like it is possible for Vivado.