Clarification of Exception for Rule 10.4

[rgamble]

The first exception to rule 10.4 states:

The binary + and += operators may have one operand with essentially character type and the
other operand with an essentially signed or essentially unsigned type;

In the examples, the following is specified as being compliant per this exception, as expected:

Code:

cha += u8a

However, the following is later included in a list of examples that are non-compliant:

Code:

u8a += cha

How can the first one be compliant and the second one not be? Was the intention of the exception that the first operand have essentially character type and the second have signed or unsigned type? Or is the example incorrect?