Fix #128076 and #131396 by reusing bound branch transport.
* bzrlib/bzrdir.py: (BzrDir.open): Add possible_transports as the last parameter.
* bzrlib/builtins.py: (cmd_update.run): Use possible_transports parameter to obtain the master branch transport and reuse it.
* bzrlib/branch.py: (Branch.open, Branch.get_master_branch, BzrBranch5.get_master_branch, BzrBranch5.update): Add possible_transports as the last parameter.
* bzrlib/workingtree.py: (WorkingTree.update): Add possible_transports as the last parameter.
* bzrlib/tests/commands/test_update.py: (TestUpdate.test_update): Ignore connections from bind.