Revert "archiso/mkarchiso: clear environment variables when chrooting"

This reverts commit 3d6651ab.

A missing $PATH breaks scripts that do not hardcode binary paths.
Fixes https://bugs.archlinux.org/task/71416 .

archiso/mkarchiso

@@ -322,18 +322,17 @@ _make_custom_airootfs() {
 
 # Install desired packages to airootfs
 _make_packages() {
-    local envvars_in_chroot=("SOURCE_DATE_EPOCH=${SOURCE_DATE_EPOCH}")
     _msg_info "Installing packages to '${pacstrap_dir}/'..."
 
     if [[ -n "${gpg_key}" ]]; then
         exec {ARCHISO_GNUPG_FD}<>"${work_dir}/pubkey.gpg"
-        envvars_in_chroot+=("ARCHISO_GNUPG_FD=${ARCHISO_GNUPG_FD}")
+        export ARCHISO_GNUPG_FD
     fi
 
     if [[ "${quiet}" = "y" ]]; then
-        env -i "${envvars_in_chroot[@]}" pacstrap -C "${work_dir}/${buildmode}.pacman.conf" -c -G -M -- "${pacstrap_dir}" "${buildmode_pkg_list[@]}" &> /dev/null
+        pacstrap -C "${work_dir}/${buildmode}.pacman.conf" -c -G -M -- "${pacstrap_dir}" "${buildmode_pkg_list[@]}" &> /dev/null
     else
-        env -i "${envvars_in_chroot[@]}" pacstrap -C "${work_dir}/${buildmode}.pacman.conf" -c -G -M -- "${pacstrap_dir}" "${buildmode_pkg_list[@]}"
+        pacstrap -C "${work_dir}/${buildmode}.pacman.conf" -c -G -M -- "${pacstrap_dir}" "${buildmode_pkg_list[@]}"
     fi
 
     if [[ -n "${gpg_key}" ]]; then
@@ -375,7 +374,7 @@ _make_customize_airootfs() {
         _msg_info "Running customize_airootfs.sh in '${pacstrap_dir}' chroot..."
         _msg_warning "customize_airootfs.sh is deprecated! Support for it will be removed in a future archiso version."
         chmod -f -- +x "${pacstrap_dir}/root/customize_airootfs.sh"
-        eval -- env -i "SOURCE_DATE_EPOCH=${SOURCE_DATE_EPOCH}" arch-chroot "${pacstrap_dir}" "/root/customize_airootfs.sh"
+        eval -- arch-chroot "${pacstrap_dir}" "/root/customize_airootfs.sh"
         rm -- "${pacstrap_dir}/root/customize_airootfs.sh"
         _msg_info "Done! customize_airootfs.sh run successfully."
     fi