Fix: bad handling of incoming data in consumer thread

This will fix Coverity issue 1019892.

The issue uncovered a more serious problem. The loop on ready FDs of the
thread was exiting at each branch thus not going on all fd. This is
problematic when the thread quit pipe is triggered and when there is
also at the same time a request for metadata from the consumer since the
metadata request could have been ignored.

This patch makes sure we go through all FDs in the loop when the thread
quit pipe or the metadata fd is triggered.

Signed-off-by: David Goulet <dgoulet@efficios.com>