bug? non-default hash sizes in tdb

[Martin Pool]

tdb (all branches) has the behaviour that when opening an existing
database, if you don't specify the right hash size, the open will fail
with EIO.  

This means for example that tdbtool can't open printing tdbs after
jra's change to increase their has size to 5000.

Wouldn't it be reasonable to ignore the hash_size parameter to
tdb_open_ex when opening an existing tdb, and just use whatever is in
the header?

-- 
Martin