xmerge: If statement is redundant

Change-Id: Ic36d66e376f6fca536a25db4b3b69b50e2b95ae2
Reviewed-on: https://gerrit.libreoffice.org/10570
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>