As discussed here: https://sourceware.org/ml/gdb-patches/2017-04/msg00157.html
A gap is not an instruction and it should not pretend to be one.
gdb.Record.instruction_history is now a list of gdb.RecordInstruction and
gdb.RecordGap objects. This allows the user to deal with Gaps in the record
in a more sane way.
The user would always get the instruction_history and function_call_history
objects of the current thread, not the thread for which the gdb.Record object
was created.
The attached testcase fails without this patch and passes with the patch.
