The class allows to check for data produced on stdout
and stderr. However, programs reporting data on stderr
usually fails with an exit code != 0. If the command
is not called with raise_on_error=False it will never
be possible to catch information from stderr. As we
don't know if programs returns a failed exit code
even on their e.g --usage message we should always
pass the no raise option to make this more useful
This commit ensures that when trying to parse the version of a tool
the comparison is done with the longest match for the given regular
expression. This solves cases such in `grub2` where the tool name
already provides some digit that could be seen as a version.
