Clear restic env vars in test

Prevents interactions from the local environment where the test is running.

repository_restic_test.go

@@ -114,7 +114,7 @@ func TestRestic(t *testing.T) {
 	}
 
 	// Check the 'restic snapshots' output.
-	output, err := exec.Command("env", "RESTIC_PASSWORD=testpass", "restic", "-r", tmpdir+"/repo", "snapshots", "--json").Output()
+	output, err := exec.Command("env", "RESTIC_REPOSITORY=", "RESTIC_PASSWORD_FILE=", "RESTIC_PASSWORD=testpass", "restic", "-r", tmpdir+"/repo", "snapshots", "--json").Output()
 	if err != nil {
 		t.Fatalf("'restic snapshots' failed: %v", err)
 	}