The input thread needs to be properly cleaned up and re-initalized before we
can start reading again in threaded mode. (Threaded input reading is used when
there is mode than one input file).
Fixes ticket #6121 and #7043.
Signed-off-by: Marton Balint <cus@passwd.hu>
(cherry picked from commit da36bcbeb78c78e493d18d3cd3ac92ea401e7031)