474   $ cd ..

   475 

   476 Detach both parents

   477 

   478   $ hg init double-detach

   479   $ cd double-detach

   480 

   481   $ hg debugdrawdag <<EOF

   482   >   F

   483   >  /|

   484   > C E

   485   > | |

   486   > B D G

   487   >  \|/

   488   >   A

   489   > EOF

   490 

   491 BROKEN: This raises an exception

   492   $ hg rebase -d G -r 'B + D + F' 2>&1 | grep '^AssertionError'

   493   AssertionError: no base found to rebase on (defineparents called wrong)

   494