library state will require explicit initialisation (but not yet)

[Jelmer Vernooij]

previously it was possible to import from bzrlib without initializing it explicitly. In bzr.dev this no longer works:

$ python fetch.py
Traceback (most recent call last):
  File "fetch.py", line 3, in <module>
    from bzrlib.branch import Branch
  File "/home/jelmer/src/bzr/bzr.dev/bzrlib/branch.py", line 2382, in <module>
    __format5 = BzrBranchFormat5()
  File "/home/jelmer/src/bzr/bzr.dev/bzrlib/branch.py", line 2082, in __init__
    self._matchingbzrdir = bzrdir.BzrDirMetaFormat1()
  File "/home/jelmer/src/bzr/bzr.dev/bzrlib/lazy_import.py", line 121, in __getattribute__
    obj = _replace()
  File "/home/jelmer/src/bzr/bzr.dev/bzrlib/lazy_import.py", line 90, in _replace
    obj = factory(self, scope, name)
  File "/home/jelmer/src/bzr/bzr.dev/bzrlib/lazy_import.py", line 211, in _import
    module = __import__(module_python_path, scope, scope, [member])
  File "/home/jelmer/src/bzr/bzr.dev/bzrlib/bzrdir.py", line 2292, in <module>
    format_name = config.GlobalStack().get('default_format')
  File "/home/jelmer/src/bzr/bzr.dev/bzrlib/config.py", line 3306, in __init__
    [bzrlib.global_state.cmdline_overrides, gstore.get_sections],
AttributeError: 'NoneType' object has no attribute 'cmdline_overrides'

Marking this as critical as almost all 3rd party users don't call .initialize.