Doing a make revert in 3.0.21a does not rollback the VFS modules to previous versions.
Funny, I was just looking at this. The problem is with lib too (WINBIND, pam_*, libsmbclient.so, libmsrpc.so. I submitted a patch for 3379 (WINBIND_NSS), but this needs more sprucing.
Would it make sense to just have bin/sbin/lib be ".old" versioned and lump several install stanzas together in Makefine.in? The I could rework 3379 as well.
The new waf build system in samba 4.0 and later did not include 'make revert' for good reason. Closing as WONTFIX, Sorry!