A recent HELP ticket came in which had an invalid MongoDB log format, which breaks wt_binary_decode.py in interesting ways. Unfortunately the developer then has to go and extract the relevant bits, however in the case of this help ticket the relevant bits were also corrupted.

To help with situations like this in the future:

1. On encountering a LOG file that doesn't look like a MongoDB log file log a message informing the user that the non-mongodb log parsing mechanism will be used. Ideally the developer will see this message and realize that the log is in an invalid format
2. When we decode the hexadecimal dump in tools/py_common/input.py we remove parts of the hex that aren't hex in order to decode the hex. This is normally fine but in this case it should've errored out with a useful error.