High frequency tone @ 48kbps stereo during frame concealment

with d4fc334d and this bitsream :

G5S4.c01_-dtx_-stereo_sw_13k2_to_128k_10fr.bin_48_eid.bfi

we can see 3 HF tones appearing between 5.15s and 5.18s. That frame is a concealment frame. The issue appears only in the right channel and is highly annoying (At least for young ears...). My guess is that some memories might not be correctly initialized.

In the next 2 figures from top to bottom:

element bitrate
element mode
lost frame indicator
floating point right channel
fixed point right channel
difference between float and fix
spectrum (2nd figure only)