e2fsprogs (optional) - btrfs-convert
reiserfsprogs (optional) - btrfs-convert
Which means they are required to be installed for btrfs-convert one of the eight binaries the btrfs-progs package provides.
]]>btrfs-convert: error while loading shared libraries: libreiserfscore.so.0: cannot open shared object file: No such file or directory
when reiserfsprogs is not installed. There is likely a similar issue with e2fsprogs missing (not tested by me).
Maybe this can be easily resolved by adjusting the build process or the dependency could be made non-optional.
Cheers!
JMH