herestring brace expansion

[Eliran Gonen]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu' 
-DCONF_VENDOR='pc' -DLOC$
uname output: Linux UU8CPLAE 4.4.0-17134-Microsoft #137-Microsoft Thu Jun 14 
18:46:00 PST 2018 x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 4.3
Patch Level: 48
Release Status: release

Description:
        “Here Strings” section in the bash(1) manual page claims that “word 
undergoes brace expansion” while it does not.

Repeat-By:
        $ read -a arr <<< 
x{a{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z},b{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o}}
        $ echo ${arr[*]}
x{a{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z},b{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o}}