[PATCH 1/2] ubi: wl: Put source PEB into correct list if trying locking LEB failed

[Ryder Wang]

> Now, e1 is the source PEB with smaller erase counter, it will be picked
> as source PEB again in next WL if it not becomes free yet.
> 
> We don't put it into scrub tree, because the scrub type PEB means that
> biflips ever happen during reading, the data is not stable anymore in
> that PEB, so UBI moves data from scrub type PEB just take the
> opportunity of WL process.
> 
> IOW, in this case, the WL won't lost keeping ec balanced whether we keep
> e1 in used tree or move it into scrub tree. It's the same thing as the
> MOVE_TARGET_WR_ERR/MOVE_TARGET_RD_ERR case.

Then what's the positive return and necessity of this patch? It looks there is few difference before and after applying the patch.