Merged from trunk 10972:10988

   Merged from trunk 10972:10988

   | 10973   | Add a new "SRC_URI.mirror" check which checks to if a uri    |
   | zmedico | listed in profiles/thirdpartymirrors is found in SRC_URI.    |
   |         | Thanks to Betelgeuse for the initial patch which has now     |
   |         | been optimized with a regex.                                 |

   | 10974   | * Add new CompositeTask._default_final_exit() method and use |
   | zmedico | it as the new generic task exit callback. * Remove erroneous |
   |         | self.wait() calls inside MergeListItem.start().              |

   | 10975   | Rename SubProcess.reg_id to _reg_id since it no longer needs |
   | zmedico | to be exposed.                                               |

   | 10976   | Add a Scheduler._digraph attribute for use in parallel build |
   | zmedico | scheduling.                                                  |

   | 10977   | Use plain sequential search for the SRC_URI.mirror check     |
   | zmedico | since the regex approach is actually much slower.            |

   | 10978   | Add a missing check in Scheduler._main_loop() to ensure that |
   | zmedico | max_jobs isn't exceeded.                                     |

   | 10979   | Add a MergeListItem.background attribute for putting a task  |
   | zmedico | in the background when max_jobs > 1.                         |

   | 10980   | Also add "background" attributes to the EbuildBuild and      |
   | zmedico | Binpkg classes.                                              |

   | 10981   | Add AsynchronousTask.background attribute and add support    |
   | zmedico | for it to the EbuildPhase class.                             |

   | 10982   | * Add background support to the SpawProcess class. * Make    |
   | zmedico | Binpkg pass the current background setting into subtasks.    |

   | 10983   | Implement parallel build support by adding new --jobs and    |
   | zmedico | --load-average options that are analogous to the             |
   |         | corresponding `make` options. Input and output handling      |
   |         | still need work to make it look better and act more friendly |
   |         | for things like interactive ebuilds that require input.      |

   | 10984   | Use a normal list instead of a deque for                     |
   | zmedico | Scheduler._pkg_queue since deque doesn't have a remove()     |
   |         | method until python-2.5.                                     |

   | 10985   | Fix ValueError triggered when Scheduler._choose_pkg()        |
   | zmedico | doesn't find a package and returns None.                     |

   | 10986   | Fix infinite loop in CompositeTask._wait().                  |
   | zmedico |                                                              |

   | 10987   | Raise an AssertionError in CompositeTask._wait() if it's     |
   | zmedico | detected that self._current_task hasn't been properly        |
   |         | updated after calling wait on it.                            |

   | 10988   | Derive PackageMerge from AsynchronousTask instead of         |
   | zmedico | CompositeTask since CompositeTask is designed for            |
   |         | self._current_task to be set.                                |

svn path=/main/branches/prefix/; revision=10997