Test the inclusion of transitive symlinks in the sandbox

(cherry picked from commit cef677d)

tests/functional/linux-sandbox.sh

@@ -61,9 +61,11 @@ testCert () {
 nocert=$TEST_ROOT/no-cert-file.pem
 cert=$TEST_ROOT/some-cert-file.pem
 symlinkcert=$TEST_ROOT/symlink-cert-file.pem
+transitivesymlinkcert=$TEST_ROOT/transitive-symlink-cert-file.pem
 symlinkDir=$TEST_ROOT/symlink-dir
 echo -n "CERT_CONTENT" > $cert
 ln -s $cert $symlinkcert
+ln -s $symlinkcert $transitivesymlinkcert
 ln -s $TEST_ROOT $symlinkDir
 
 # No cert in sandbox when not a fixed-output derivation
@@ -78,8 +80,9 @@ testCert missing fixed-output "$nocert"
 # Cert in sandbox when ssl-cert-file is set to an existing file
 testCert present fixed-output "$cert"
 
-# Cert in sandbox when ssl-cert-file is set to a symlink to an existing file
+# Cert in sandbox when ssl-cert-file is set to a (potentially transitive) symlink to an existing file
 testCert present fixed-output "$symlinkcert"
+testCert present fixed-output "$transitivesymlinkcert"
 
 # Symlinks should be added in the sandbox directly and not followed
 nix-sandbox-build symlink-derivation.nix -A depends_on_symlink