Merged from trunk 9461:9467

   Merged from trunk 9461:9467

   | 9462    | * Optimize parallel-fetch to avoid redundant checksum        |
   | zmedico | verification. * Add parallel-fetch to the default FEATURES   |
   |         | since it is more efficient now.                              |

   | 9463    | Bug #42456 - When a checksum failure occurs during fetch,    |
   | zmedico | use a new PORTAGE_FETCH_CHECKSUM_TRY_MIRRORS config variable |
   |         | to control how many mirrors should be tried before aborting  |
   |         | the download. This type of behavior used to be enabled only  |
   |         | in --fetchonly mode but now it's enabled for all fetch()     |
   |         | calls.                                                       |

   | 9466    | Fix grammar.                                                 |
   | zmedico |                                                              |

   | 9467    | Fix an UnboundLocalError for 'pkgindex'.                     |
   | zmedico |                                                              |

svn path=/main/branches/prefix/; revision=9468