Kasper Osterbye schrieb am Dienstag, 26. April 2022 14:50:51 (+02:00):

I have now raised it as an issue on the issue tracker

Issue #11165 in https://github.com/pharo-project/pharo/issues/11165

add two new methods - prefixedBy: and suffixedBy: to handle the empty prefix/suffix correctly
add comments to beginsWith: and endsWith: referring to the two new methods

The problem is that there is client code which depend on the (wrong) implementation of the beginsWith and endsWith methods.