fetchurl: change to grep -E to fix #8561

Close #21861.

+1 -1
+1 -1
pkgs/build-support/fetchurl/write-mirror-list.sh
··· 1 1 source $stdenv/setup 2 2 3 3 # !!! this is kinda hacky. 4 - set | grep '^[a-zA-Z]\+=.*://' > $out 4 + set | grep -E '^[a-zA-Z]+=.*://' > $out