I made a mistake about the compatibility. I was looking at the 2.2.1 revision. However, I am not completely wrong if you look at the following revision:
https://hg.adblockplus.org/adblockplus/rev/c8cfe3956af2 This is three revisions after upstream's 2.1.1 release. The three revisions are trivial, one is a comment change and the others are simply changing version numbers in the source. The following are links to upstream in order ascending: - https://hg.adblockplus.org/adblockplus/rev/080a46e3d6d2 - https://hg.adblockplus.org/adblockplus/rev/cb334b336096 - https://hg.adblockplus.org/adblockplus/rev/c8cfe3956af2 So instead of changing to 20.0a1 you only need to change the break requirement to 17.0a1.
