Possible bug in xPert?

[James Kwon]

Hello, 

In the lines below, I take Lie derivatives of the perturbed Sqrt[-Detg[]]. The following two lines are giving me different results, which should give me the same result as the top. The difference is whether I put ExpandPerturbation before or after LieDToCovD. Is this a possible bug? 

ToCanonical[
 ContractMetric[
   LieDToCovD[
    ExpandPerturbation@LieD[v[a]][Perturbation[Sqrt[-Detg[]], 1]], CD]]/
  Sqrt[-Detg[]]]

ToCanonical[
 ContractMetric[
   ExpandPerturbation@
    LieDToCovD[LieD[v[a]][Perturbation[Sqrt[-Detg[]], 1]], CD]]/
  Sqrt[-Detg[]]]

Thank you!