gistfile1.txt

  /nix/store/vv9ij1wd45vckp9bm1xp776zb51h4wcq-gcc-wrapper-9.3.0/bin/cc   -o scripts/kconfig/nconf scripts/
kconfig/nconf.o scripts/kconfig/nconf.gui.o scripts/kconfig/confdata.o scripts/kconfig/expr.o scripts/kcon
fig/lexer.lex.o scripts/kconfig/menu.o scripts/kconfig/parser.tab.o scripts/kconfig/preprocess.o scripts/k
config/symbol.o scripts/kconfig/util.o   -L /nix/store/4wsq4c9v3hjlmbiaq8d8r1al7pm27jib-ncurses-6.2/lib -l
ncursesw -lmenuw -lpanelw
cho "no-op"
/bin/sh: cho: not found
make[1]: *** [scripts/kconfig/Makefile:48: nconfig] Error 127

guessing this was introduced by the gnarly sed expression in kernel/builder.nix 

        sed -i"" -e 's/$< .*$(Kconfig)/echo "no-op"/' scripts/kconfig/Makefile