merge revision(s) 35625: [Backport #6618]
* thread.c (rb_threadptr_execute_interrupts_common): test_signal_requiring of test/ruby/test_signal.rb fail if the sub process is killed on waiting IO in lex_io_gets in rb_load_file in rb_load_internal in require. This is because (1) the process receive the killing signal in rb_thread_io_blocking_region in rb_read_internal in lex_io_gets. (2) set th->errinfo as INT2FIX(TAG_FATAL) at rb_threadptr_execute_interrupts_common. (3) escape rb_load_file in rb_load_internal and jump to EXEC_TAG() without set loaded as TRUE. (4) call first rb_exc_raise(GET_THREAD()->errinfo); because loaded is FALSE as above. this errinfo should be an exception object but this is INT2FIX(TAG_FATAL). Don't call first rb_exc_raise if GET_THREAD()->errinfo is Fixnum.