optiionally patch stderr and stdout in the context manager

Signed-off-by: Alfredo Deza <alfredo@deza.pe>
allow an optional patch kwarg to check_call

Signed-off-by: Alfredo Deza <alfredo@deza.pe>
do not patch stdout/stderr on mon start

Signed-off-by: Alfredo Deza <alfredo@deza.pe>
Merge pull request #44 from alfredodeza/5895-2

Do not attempt to capture stdout/stderr on some `check_calls` D=