In the middle of a recent "yum update", this started happening:

$ perl -e 'use DB_File;'

DB_File needs compatible versions of libdb & db.h
        you have db.h version 4.6.18 and libdb version 4.6.19
Compilation failed in require at -e line 1.
BEGIN failed--compilation aborted at -e line 1.
$ 

I think the perl RPM needs to create a build-time dependency on the version of
db against which it was linked, to prevent yum update from installing a new db
version when no corresponding relinked perl is available.