On certain error conditions there is a code snippet that checks whether the last component of the path has a trailing dot or space or a leading space. Skip this check if the last component is empty, i.e., if the path ends with a backslash. This avoids an assertion failure if the trailing backslash is the only backslash in the path, as is the case for a DOS drive 'X:\'. Addresses: https://cygwin.com/ml/cygwin/2019-12/msg00016.html
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