P4 may preserve only the most recent copy of a file's data, automatically
"purging" the file data from older changelists when a new one is submitted.
That data is gone, and can't be accessed even from P4.
When importing such a file, we create an empty file so we can record that it
existed (e.g. which changelist introduced it).
Therefore, we include it in the list of filelogs we import, and we record that
changelists modified the file too. The file just has empty contents in the