hg log shows nothing after upgrade.

[Rob Landley]

Last week I backed up my home partition and reinstalled from ubuntu
12.04 to 14.04, and now my old mercurial directories don't work. "hg
log" shows nothing, hg identify says:

  warning: ignoring unknown working parent 382d5b9ff2d5!
  000000000000+ tip"

hg status sort of seems to still work (shows 4 modified files, can
figure out which ones aren't tracked), but hg diff shows those 4 files
diffed against /dev/null...

Does this sound familiar to anybody? If I pull new repos from the server
those work, but the new mercurial in 14.04 doesn't seem to be able to
parse the old repository format from 12.04...?

Rob