unexpected result for creating directory tree using callProcess or callCommand

#### shell command :-
mkdir -p ./{new/{new1,new2},old}

#### tested with :-
callProcess "mkdir" ["-p" , "./{new/{new1,new2},old}"]
callCommand "mkdir -p ./{new/{new1,new2},old}"

#### result :-
.
├── {new
│ └── {new1,new1},old}

#### expected output :-
tree .
.
├── new
│   ├── new1
│   └── new1
└── old

I printed shell command with :-
showCommandForUser "mkdir" ["-p" , "./{new/{new1,new2},old}"]

### output :- "mkdir -p './{new/{new1,new2},old}'"
this single single quotes around directory name causing problem
how can i fix this

Reproduce the mkdir examples with callProcess, callCommand, and showCommandForUser, then read the behavior of those entry points and how shell expansion is handled. Compare the observed and expected directory trees; the issue is done when the command behavior is corrected or the distinction and intended usage are clearly documented with coverage for the reported case.

Written by the indexing model from the issue text.