Merged from trunk -r13290:13296

   Merged from trunk -r13290:13296

|13291  |Add portdbapi support for a metadata/layout.conf file which specifies information |
|zmedico|about the repository layout. Currently, only a single "masters" attribute is      |
|       |supported, which is used to specify names of repositories which satisfy           |
|       |dependencies on eclasses and/or ebuilds. Each repository name should correspond   |
|       |the value of a repo_name entry from one of the repositories that is configured via|
|       |the PORTDIR or PORTDIR_OVERLAY variables. Since layout.conf is now used to control|
|       |eclass inheritance, it is now safer to use overlays which contain forked eclasses |
|       |have names identical to those from the main tree. Such eclasses will only apply to|
|       |their containing repository and any other repositories which reference their      |
|       |containing repository via layout.conf. This solves bug #124041 by containing      |
|       |eclass overrides so that they don't necessarily apply to all ebuilds. Thanks to   |
|       |Alistair Bush <ali_bush@g.o> for his initial patch for layout.conf support in     |
|       |repoman (will be merged later). See the "QA Overlay Layout support" thread on the |
|       |gentoo-dev mailing list for more information:                                     |
|       |http://archives.gentoo.org/gentoo-dev/msg_33c61550b4ed2b7b25dd5a4110e1ec81.xml    |

|13292  |Add a --repo option, allowing cache to be generated for overlays.                 |
|zmedico|                                                                                  |

|13293  |Fix code in the portdbapi constructor to cache eclass_cache.cache instances where |
|zmedico|appropriate.                                                                      |

|13294  |Replace references to portdbapi.eclassdb with appropriate references for the      |
|zmedico|specific repo.                                                                    |

|13295  |Add support to repoman for using layout.conf to control which repositories are    |
|zmedico|used to satisfy dependencies. Thanks to Alistair Bush <ali_bush@g.o> for the      |
|       |initial patch. See the "QA Overlay Layout support" thread on the gentoo-dev       |
|       |mailing list for more information:                                                |
|       |http://archives.gentoo.org/gentoo-dev/msg_33c61550b4ed2b7b25dd5a4110e1ec81.xml    |

|13296  |Fix some _doebuild_exit_status_check() calls so that they only happen when the    |
|zmedico|bash process exits successfully (for consistency with usage elsewhere). When      |
|       |calling this functions, we're mainly concerned about false success, and we always |
|       |want to allow things like using bashrc die hooks to clean up $PORTAGE_BUILDDIR for|
|       |users that are building in tmpfs (in which case the exit status file may be       |
|       |removed before bash exits).                                                       |

svn path=/main/branches/prefix/; revision=13319