Is it fixed on main

.github/workflows/ci.yml

@@ -17,6 +17,10 @@ jobs:
           logger: pretty
           log-directives: nix_installer=trace
           backtrace: full
+          nix-installer-branch: main
+          extra-conf: |
+            experimental-features = impure-derivations
+      - run: cat /etc/nix/nix.conf
       - name: echo $PATH
         run: echo $PATH
       - name: Test `nix` with `$GITHUB_PATH`

action.yml

@@ -159,20 +159,19 @@ runs:
           echo "Set NIX_INSTALLER_NIX_PACKAGE_URL=$NIX_INSTALLER_NIX_PACKAGE_URL"
         fi
 
-        NIX_EXTRA_CONF=""
-        NEWLINE='
-        '
+        NIX_EXTRA_CONF_FILE=$(mktemp --suffix=nix-installer-extra-conf)
+
         if [ -n "${{ inputs.extra-conf }}" ]; then
-          NIX_EXTRA_CONF="${{ inputs.extra-conf }}"
+          echo "${{ inputs.extra-conf }}" >> ${NIX_EXTRA_CONF_FILE}
         fi
         if [ -n "${{ inputs.github-token }}" ]; then
-          NIX_EXTRA_CONF="${NIX_EXTRA_CONF:+$NIX_EXTRA_CONF$NEWLINE}access-tokens = github.com=${{ inputs.github-token }}"
+          echo "access-tokens = github.com=${{ inputs.github-token }}" >> ${NIX_EXTRA_CONF_FILE}
         fi
         if [ "${{ inputs.trust-runner-user }}" == "true" ]; then
-          NIX_EXTRA_CONF="${NIX_EXTRA_CONF:+$NIX_EXTRA_CONF$NEWLINE}trusted-users = root $USER"
+          echo "trusted-users = root $USER" >> ${NIX_EXTRA_CONF_FILE}
         fi
-        if [ -n "$NIX_EXTRA_CONF" ]; then
-          export NIX_INSTALLER_EXTRA_CONF="$NIX_EXTRA_CONF"
+        if [ -n "$NIX_EXTRA_CONF_FILE" ]; then
+          export NIX_INSTALLER_EXTRA_CONF=$(cat ${NIX_EXTRA_CONF_FILE})
           echo "Set NIX_INSTALLER_EXTRA_CONF=$NIX_INSTALLER_EXTRA_CONF"
         fi