Substitution PE parsed wrong or doesn't work correctly

[Jan Schampera]

Hello,

Tested versions:
- 4.1.2(1)-release
- 3.2.39(1)-release

Reproduce by:
  string="1/2 3="
  echo ${string//[= /]}

Expected result:
  123

Actual result:
  1/2 3=

Workaround: Escape the "inner" slash with a backslash.


Within a bracket expression, the slash should lose its special meaning. 
It looks like the construct is incorrectly parsed (because it uses 
slashes itself), but I may be wrong, I didn't inspect the code.

Regards,
Jan