redirect called with undefined after a custom redirect on form save

[ThieryMichel]

What you were expecting:
I use a custom redirect on an edit form: We can edit a teaser from a list of teaser scheduling, and once saved we want to return to the list of scheduling.
For that we use a FormWithRedirect along with a function as a redirect prop.

What happened instead:
On submit, there is a first redirect toward the planned page, then immediately afterward a redirect toward "/" then finally toward the list.

Related code:
Until the 3.14.2 version this worked, but it broke on 3.14.3.
To be precise the bug was introduced by this commit #6145
The redirect created by useRedirect is called with undefined after the first redirect.
Before the change this resulted in a push toward { pathname: undefined } which was ignored.
Since the change in useRedirect this became: {pathname: "/", search: "", hash: ""} causing the bug.

Environment

• React-admin version:
• 3.14.2
• This bug was introduced by this change: Fix useRedirect does not handle query strings #6145
• Before that the undefined redirect had no effect.
• React version: 16.13.1
• Browser: chrome
• Stack trace (in case of a JS error):

[ThieryMichel]

Found the cause, I had a redirect props that did the redirect itself thus returning undefined.
Which in turn caused the bug when react-admin tried to use its return value.
Fixed it by having it return the url instead.