cubicweb #1942760 python 2.7 don't show DeprecationWarning by default [resolved]

so those should be explicitly enabled when running in debug mode

prioritynormal
typebug
done in3.13.6
load0.100
load left0.000
closed by#ce8a4de2ecf1 [warnings] explicitly ask to show DeprecationWarning in debug mode (closes #1942760)