Confusing behavior of itset define (defset) with regards to width

[simark]

So, we have a few threads:

(gdb) i th
  Id   Target Id         Frame 
* 1.1  Thread 0x7ffff7fc5740 (LWP 9277) "test_pthread" break_here () at test_pthread.c:112
  1.2  Thread 0x7ffff77f6700 (LWP 9281) "test_pthread" 0x00007ffff7bcaf1c in __lll_lock_wait ()
   from /lib/x86_64-linux-gnu/libpthread.so.0
  1.3  Thread 0x7ffff6ff5700 (LWP 9282) "test_pthread" 0x00007ffff7bcaf1c in __lll_lock_wait ()
   from /lib/x86_64-linux-gnu/libpthread.so.0
  1.4  Thread 0x7ffff67f4700 (LWP 9283) "test_pthread" 0x00007ffff7bc923c in pthread_barrier_wait
    () from /lib/x86_64-linux-gnu/libpthread.so.0
  1.5  Thread 0x7ffff5ff3700 (LWP 9284) "test_pthread" 0x00007ffff7bc923c in pthread_barrier_wait
    () from /lib/x86_64-linux-gnu/libpthread.so.0
  1.6  Thread 0x7ffff57f2700 (LWP 9285) "test_pthread" 0x00007ffff7bc923c in pthread_barrier_wait
    () from /lib/x86_64-linux-gnu/libpthread.so.0
  1.7  Thread 0x7ffff4ff1700 (LWP 9286) "test_pthread" 0x00007ffff7bcaf1c in __lll_lock_wait ()
   from /lib/x86_64-linux-gnu/libpthread.so.0
  1.8  Thread 0x7ffff47f0700 (LWP 9287) "test_pthread" 0x00007ffff7bcaf1c in __lll_lock_wait ()
   from /lib/x86_64-linux-gnu/libpthread.so.0
  1.9  Thread 0x7ffff3fef700 (LWP 9288) "test_pthread" 0x00007ffff78460fb in ?? ()
   from /lib/x86_64-linux-gnu/libc.so.6

And the current width is default:

(gdb) itfocus 
Focus is `dt1.1'.
Current inferior is 1.
Current thread is 1.

I try to define a workers set that contains two threads:

(gdb) itset define workers (t1.2,t1.3)

It ends up containing all the threads of inferior one:

(gdb) itset view 
...
workers contains:
  inferiors: 1
  threads: 1, 2, 3, 4, 5, 6, 7, 8, 9
  cores: 3, 2, 3, 1, 1, 1, 1, 3, 1

That's probably because the default width for that operation is the inferior (or all, I haven't tried with more than one inferior), something like that. When I set the width to thread:

(gdb) itfocus t itset define workers2 (t1.2,t1.3)

The set only contains the specified threads:

(gdb) itset view
...
workers contains:
  inferiors: 1
  threads: 1, 2, 3, 4, 5, 6, 7, 8, 9
  cores: 3, 2, 3, 1, 1, 1, 1, 3, 1
workers2 contains:
  inferiors: 1
  threads: 2, 3
  cores: 2, 3

Shouldn't the default width for the defset command be thread? It seems counter intuitive if it automatically includes more threads than the user specified.