detecting readline in top-level ./configure is no guarantee of readline support
This is about readline in 6.8.x, but presumably the same issue applies for editline in 6.10.x.
The top level
./configure script can detect readline, but then the readline package's
./configure script can fail to do so. Presumably this is because that
./configure script does not get passed the
--with-readline-libraries= flags. The top level
./configure script does not mention anything about these flags or readline in general.
Presumably the top level configure script's readline checks can work if readline happens to be in the same place as was specified for gmp with the flags
The way in which it silently gets automatically deseletected despite the reassuring messages from the top level
./configure is quite confusing. It might be nice if we could say that we really want a feature and have it fail if it could not comply rather than silently turning the feature off.