Comment 23 for bug 1001189

> Apparently "gdbm-1.9.1 (already in Rawhide) provides different magic values for 32 and 64 bits, so we can
> discover what system the file was created on if we use this new version"

Yes... for example, search for the string "Is the magic number good?" in
  http://git.gnu.org.ua/cgit/gdbm.git/tree/src/gdbmopen.c

So with a newer version of libgdbm3, man-db should get a GDBM_BYTE_SWAPPED or GDBM_BAD_FILE_OFFSET error code when attempting to open an wrong-architecture index.db file, rather than a "successful" open() followed by a seg fault or a fatal gdbm error when attempting to read from the file, as happens now....