master
Ignore "n/a" from lsb_release output allowing other sources to be honored
Added testcases with failing lsb_release commands.
Fixed issue #36: Unreliable id() and meaning of base(). Details: - Added support for a reliable distro ID returned by id(). The normalization happens only for id(); the *_release_info() and get_*_release_attr() methods do not provide a reliable ID; these methods provide the values as obtained from the respective sources. - The set of distros for which the ID is reliable has been initially taken from the _DIST_TO_BASE dict. A TODO has been added to make sure we review that list. - These reliable distros are documented with their ID values in the description of the id() method. - Removed the base() method and, because it was no longer used, its _DIST_TO_BASE dict. - Adjusted testcases and standalone query script to the changed behavior of the id() method. - Documented a TODO in the TestOverall test class for those distros that have reliable IDs, but have no testcase representation so far. - Changed the mocking concept for the TestLSBRelease class to also use the concept from DistroTestCase. This became necessary because the previous mocking concept was making assumptions about the implementation that were no longer met. As part of that, the LSB output files in the special directory became simple lsb_release scripts that print a hard coded set of lines, in the testdistros directory.