BUG: Avoid try/except in blocks, fix setitem bug in datetimelike EA
The initial impetus for this was avoiding two try/excepts in Block methods (i.e. the diff in internals.blocks).  This uncovered the bug in DTA/TDA, which accounts for the rest of the diff.
does this need rebase? as it included the just merged set indexing patch > does this need rebase?

should be OK as is thanks