ISAC steerers with non-zero length not being converted correctly
For elements of type 'ecb' with a non-zero length, xml2optr appears to subtract that length equally from downstream and upstream drifts to 'make space' for the steerer (seems like that is what it does for quads). HOWEVER, it does not add the necessary drift that would represent the steerer's length. The end result is that the length of the steerer is subtracted from the model everywhere that there is one, making the model incorrect.
@tplanche @oshelb you should be aware of this. @pjung can you fix it?
Edited by Spencer Kiy