Dear Adrian,
Thank you for this explanation about the cause of the FTBFS on mipsel.
If I understand well, the "cannot allocate memory" error with lzma on
mipsel is caused by the high compression level 9, while the default
value for xz compression is 6.
This modification was introduced in June 2012:
https://anonscm.debian.org/cgit/collab-maint/geneweb.git/commit/?id=16cddde963e4169c09bfe49cb6949fe0dc484f0c
At first sight, I don't see any reason to use compression level 9, so I
will apply your patch on the git repository.
Best regards,
Guillaume Brochu