I notice when I run zdump like this:

zdump /usr/share/zoneinfo/America/New_York

The output is normal:
America/New_York  Sun Oct 28 18:23:35 2018 EDT

But if I change to the America directory...
cd /usr/share/zoneinfo/America
zdump ./New_York

The output is missing the abbreviation:
./New_York  Sun Oct 28 22:23:48 2018

Is this expected? Seems like a subtle bug to me.  The abbreviations are also missing with -v output.

(Ran on Ubuntu Linux 16.04.5 LTS)

Thanks,
Matt