Not to eat Metadata parsing error

Exception raised while resolving metadata is treated as database
exception and eaten.

A few testing errors are revealed after metadata parsing error is
propagated to callers.

Fixes bug #1207193

Change-Id: I3b5cc5fed3896b7fe59533c7d09f0226e5cf5ad9
Revert "Add missing _ imports to allow doc generation"

This change reverts commit 0453785f3f7b2a578b433cb0544394aac9bcfb95 and
fixes a bug where the _() was not being recognized when building the
documentation while preserving the delayed translation of error
messages.

Closes-Bug: #1211507
Related-Bug: #1209413

Change-Id: I5d52941e1f08ec656f7279efb6cdf496d81861da
Merge "Revert "Add missing _ imports to allow doc generation""
Merge "Not to eat Metadata parsing error"