c5dccea libopkg: fix md5sum calculation
7cad0c0 opkg_verify_integrity: better logging and error conditions
14d6480 download: purge cached packages that have incorrect checksum
456efac download: factor out the logic for building cache filenames
b145030 libopkg: factor out checksum and size verification
74bac7a download: remove compatibility with old cache naming scheme
Fixes: FS#2690
Signed-off-by: Baptiste Jonglez <git@bitsofnetworks.org>