qibuild: use ipdb when --pdb is used if it is available
qibuild: use ipdb when --pdb is used if it is available

No good reason not too :)

dmerejkowsky/qibuild,dmerejkowsky/qibuild,dmerejkowsky/qibuild,dmerejkowsky/qibuild,aldebaran/qibuild,aldebaran/qibuild,aldebaran/qibuild,aldebaran/qibuild,dmerejkowsky/qibuild