cubicweb #2556426 missing a __contains__ method on QueryCache [waiting feedback]

The docstring og the QuesryCache class (utils.py) states that the QueryCache is:

a minimalist dict-like object to be used by the querier
and native source (replaces lgc.cache for this very usage)

however there is no __contains__ method.

priorityminor
typeenhancement
done in<not specified>
load0.100
load left0.100
closed by<not specified>