So it appears this broke a year ago, and I'm just noticing it now because it finally rolled into Fusion/Workstation.  Reverting to pre-ovftool 4.x variants of my scripts fixes ovf export, so rather than alias the deprecated --allowAllExtraConfig flag back to the surviving --allowExtraConfig flag, they elected to just break it.   So for the next guy to trip over this one; include both flags and it works on 4.1 and 4.2.  Each version seems to ignore the flag it considers extraneous.