Both new and old format pagecount files can contain empty title.

e.g. in stat1002:/mnt/data/xmldatadumps/public/other/pagecounts-all-sites/2015/2015-01>

zgrep -P "^ab.*28331" pagecounts-20150127-110000.gz
yields
'ab 1 28331' (notice two consecutive spaces)

As this occurs in both old and new files this is probably a very old bug.
This may break post-processing scripts that always expect four non-empty fields
(it did break the daily/monthly aggregation script).

I'll patch this in my script, so for now I'm good, but empty title can't occur so something got lost.