The output from `uname -r` differs from the directory name created under /usr/src during emerge:
tfoerste@n22 ~ $ ll /usr/src/
lrwxrwxrwx 1 root root 22 Jan 22 10:32 linux -> linux-2.6.15-gentoo-r1
drwxr-xr-x 20 root root 4096 Jan 22 15:14 linux-2.6.15-gentoo-r1
drwxr-xr-x 20 root root 4096 Jan 26 12:59 linux-2.6.15-usermode
lrwxrwxrwx 1 root root 21 Jan 22 10:43 uml -> linux-2.6.15-usermode
tfoerste@n22 ~ $ uname -r
For the gentoo kernel itself and for the vanilla kernel the directory name matches `uname -r`, which is useful if somebody appends its own localversin to the kernel info.
What about adding ypur initial "-bs1" to the kernel info & the directory or removing it ?
It has always been this way for usermode-sources and I feel that changing it would cause more harm than good. Also, it might not be around much longer.
You can always access the tree via /lib/modules/$(uname -r)/build