  The B -> X_s gamma branching ratio is currently measured with around 5%
accuracy. Further improvement is expected from Belle II. To match such a
precision on the theoretical side, evaluation of O(alpha_s^2) corrections to
the partonic decay b -> X_s^part gamma are necessary, which includes the b -> s
gamma, b -> s g gamma, b -> s g g gamma, b -> s qbar q gamma decay channels.
Here, we evaluate the unrenormalized contribution to b -> s gamma that stems
from the interference of the photonic dipole operator Q_7 and the
current-current operators Q_1 and Q_2. Our results, obtained in the cut
propagator approach at the 4-loop level, agree with those found in parallel by
Fael et al. who have applied the amplitude approach at the 3-loop level.
Partial results for the same quantities recently determined by Greub et al.
agree with our findings, too.
