Merged from trunk -r12664:12669

   Merged from trunk -r12664:12669

   | 12665   | When loading vdb_metadata.pickle inside                      |
   | zmedico | vardbapi._aux_cache_init(), in order to avoid an extreme     |
   |         | performance issue, disable buffering when opening the file   |
   |         | under python-3.0. Unfortunately, performance is still poor   |
   |         | relative to python-2.x, but buffering makes it much worse.   |

   | 12666   | For python-3.0 compatibility, open files in binary mode      |
   | zmedico | inside SpawnProcess._start().                                |

   | 12667   | Inside summarylist(), it's possible for                      |
   | zmedico | myglsa.packages.keys() to contain unicode objects, which     |
   |         | trigger and exception like this: File                        |
   |         | "//usr/lib64/portage/pym/portage/dep.py", line 535, in       |
   |         | __init__ obj_setattr(self, x, getattr(s, x)) AttributeError: |
   |         | 'unicode' object has no attribute '__eq__' To solve this     |
   |         | problem, convert unicode objects to plain str before passing |
   |         | them to the portage api.                                     |

   | 12668   | Inside portage.spawn(), open files for logfile handling in   |
   | zmedico | binary mode, for compatibility with python-3.0.              |

   | 12669   | Revert r12639 and use string.ascii_letters for python-3.0    |
   | zmedico | compatibility.                                               |

svn path=/main/branches/prefix/; revision=12671