Recent change in JOSM has broken some older *.osm files

[rickmastfan67]

Alright, I have this older (from February) *.osm file that a friend made for me out of the 2010 TIGER data so I could use it to replace/fix/add roads to OSM where necessary locally.

Well, I had been able to open the file with no problems in JOSM up until recently. It last opened in r4164. Every release after that, it refuses to open. When I try to open it in r4172 or r4174, the following message shows up:

Could not read file 'TIGER2010_Allegheny_PA.osm'.
Error is:
Line 1 column 60: Unsupported version: 0.3 (at line 1, column 60)

Back in r4164 and previous versions, I did notice this when I opened the file in the CL:

Undefined element: 'osmChange' found in input stream. Skipping.
Undefined element: 'modify' found in input stream. Skipping.

But I didn't pay attention to it since it was "skipped".

Is this something that can be fixed in JOSM to have the file work again, or is there something I should fix in the osm file so that it can be loaded in JOSM versions later than r4164?