Merged from trunk 10928:10943

   Merged from trunk 10928:10943

   | 10929   | Bug #230525 - Work around ObjectProxy breakage in `portageq  |
   | zmedico | vdb_path`.                                                   |

   | 10930   | Add a PollConstants class to serve as a layer of indirection |
   | zmedico | for accessing select.POLL* attributes which do not exist on  |
   |         | interix. Thanks to grobian for reporting.                    |

   | 10931   | TODO: For parallel scheduling, everything in MergeListItem   |
   | zmedico | needs asynchronous execution support (start, poll, and wait  |
   |         | methods).                                                    |

   | 10932   | Convert EbuildFetcher to an asynchronous interface: * Rename |
   | zmedico | EbuildFetcher to EbuildFetchPretend. * Rename                |
   |         | EbuildFetcherAsync to EbuildFetcher.                         |

   | 10933   | Make EbuildBuild inherit from EbuildBuildDir since it's      |
   | zmedico | going to hold the build dir lock while it runs               |
   |         | asynchronously.                                              |

   | 10934   | Make Binpkg inherit from EbuildBuildDir since it's going to  |
   | zmedico | hold the build dir lock while it runs asynchronously.        |

   | 10935   | * Implement a new binarytree.digestCheck() method and use it |
   | zmedico | to check digests for binary packages. * Split out a          |
   |         | AsynchronousTask base class from SubProcess. * Derive a new  |
   |         | BinpkgVerifier class from AsynchronousTask. Even though this |
   |         | is not really asynchronous yet, it can fake the interface by |
   |         | doing everything in the start() method.                      |

   | 10936   | Rename BinpkgFetcherAsync class to BinpkgFetcher and use it  |
   | zmedico | to replace the older class with the same name                |

   | 10937   | Remove unused variable.                                      |
   | zmedico |                                                              |

   | 10938   | Use the EbuildPhase class to execute the "clean" phase       |
   | zmedico | asynchronously.                                              |

   | 10939   | Add async support to EbuildBinpkg by making it inherit from  |
   | zmedico | EbuildPhase.                                                 |

   | 10940   | Add a new CompositeTask class which can be used to combine   |
   | zmedico | separate AsynchronousTask instances into a single instance.  |
   |         | The CompositeTask instance used task exit listeners as a     |
   |         | means to (asynchronously) trigger progression from one       |
   |         | subtask to the next. This technique is used to group         |
   |         | together all the ebuild phases executed by EbuildExecuter,   |
   |         | and should be useful for grouping many more sets of tasks    |
   |         | into similar composite tasks.                                |

   | 10941   | Fix CompositeTask.cancel() so that it's safe to call when    |
   | zmedico | there is no running task.                                    |

   | 10942   | Make EbuildExecuter inherit from AsynchronousTask.           |
   | zmedico |                                                              |

   | 10943   | Split out common code from CompositeTask and EbuildExecuter  |
   | zmedico | into a new CompositeTask class and rename the old            |
   |         | CompositeTask class to TaskSequence.                         |

svn path=/main/branches/prefix/; revision=10967