If I set STD_CELL_LIBRARY and re-run "make pdk", it seems that flow.tcl still doesn't get the new library. I'm doing this like:

export STD_CELL_LIBRARY="sky130_fd_sc_ls"
make pdk
make mount
echo $STD_CELL_LIBRARY (not set, so I set it again)
export STD_CELL_LIBRARY="sky130_fd_sc_ls"
./flow.tcl -design spm
...
INFO]: Extracting the number of available metal layers from /home/mrg/openlane/pdks/sky130A/libs.ref/sky130_fd_sc_hd/techlef/sky130_fd_sc_hd.tlef
[ERROR]: during executing: "python3 /openLANE_flow/scripts/extract_metal_layers.py -t /home/mrg/openlane/pdks/sky130A/libs.ref/sky130_fd_sc_hd/techlef/sky130_fd_sc_hd.tlef -o /openLANE_flow/designs/spm/runs/05-04_16-57/tmp/met_layers_list.txt"
[ERROR]: Exit code: 1
[ERROR]: Last 10 lines:
Traceback (most recent call last):
  File "/openLANE_flow/scripts/extract_metal_layers.py", line 37, in <module>
    with open(techlef_name, "r") as f:
FileNotFoundError: [Errno 2] No such file or directory: '/home/mrg/openlane/pdks/sky130A/libs.ref/sky130_fd_sc_hd/techlef/sky130_fd_sc_hd.tlef'