tiny details in symbolic min and max

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Component: **symbolics**

Author: **Frédéric Chapoton**

Branch/Commit: **[`d097f77`](https://github.com/sagemath/sagetrac-mirror/commit/d097f7769f94889054e7f57e6bcd27654de0a41e)**

Reviewer: **Matthias Koeppe**

_Issue created by migration from https://trac.sagemath.org/ticket/34738_

