Enblend

When combining large images (output size approx >=25000x5000px) enblend
creates horizontal lines like:
http://downloads.moeeeep.com/panoramabug/t1/output.png
It seems to me, that these horizontal lines only occur on a 360° panorama,
when an image has to be "split" like:
http://downloads.moeeeep.com/panoramabug/t1/example.png
This brought me the idea to emulate this behavior and to create a testcase
out of it:
Warning, huge files ahead (30000x10000px)
- The panorama file that enblend should see in its memory:
http://downloads.moeeeep.com/panoramabug/t1/t0_lzw.tif (881K)
- The split file:
http://downloads.moeeeep.com/panoramabug/t1/t1_lzw.tif (775K)

I did put them into a folder an run:
enblend -v -o out_lzw.tif t0_lzw.tif t1_lzw.tif
Output (screenshot):
http://downloads.moeeeep.com/panoramabug/t1/output.png (22K)

Here's the gimp file for those who want to extend the example:
http://downloads.moeeeep.com/panoramabug/t1/t.xcf (3.1M)

The number of horizontal lines seem to correlate to the number of
images split at the edge of the image.

enblend version: 3.2
environment: http://downloads.moeeeep.com/panoramabug/t1/system.txt