After the recent lvm2 upgrade in /testing, creating snapshots generates some
worrisome error messages.  For example, creating a snapshot of the "home" lv
in the "raid5" vg:

raid5-home--snap: event registration failed: 29599:3 libdevmapper-event-lvm2snapshot.so dlopen failed: /lib/x86_64-linux-gnu/liblvm2cmd.so.2.02: symbol dm_report_field_string_list_unsorted, version Base not defined in file libdevmapper.so.1.02.1 with link time reference
raid5/snapshot0: snapshot segment monitoring function failed.

Despite this looking scary, the snapshot does appear to have been created
just fine.  This didn't happen with the prior version in testing, namely
2.02.109-1.  I presume this is because the dmeventd modules were enabled in
lvm.conf in the new version.  Given all the .so's in this chain came from
the same release of the same lvm2 source pacakge, however, it seems very
strange that it's complaining about symbol versions like this.

The symbol does seem to be there, so I guess it's a versioning issue?

$ nm -D /lib/x86_64-linux-gnu/libdevmapper.so.1.02.1 | grep dm_report_field_string_list_unsorted
0000000000026280 T dm_report_field_string_list_unsorted

Is there "dmeventd -R" called in update script? This one should be
called each time dmeventd is updated to pick up any changes
in libdevmapper (the dmeventd is reexecuted and the monitoring
state is transferred from the old dmeventd instance).