[session] don't silently ignore commits commits while in the precommit or postcommit phase are silently ignored. This is OK in precommit since there'll be a commit afterwards anyway; OTOH in postcommit it may surprise the developer who didn't read the documentation for postcommit operations carefully enough. Related to #4383922.

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"""cubicweb-%(cubename)s application package

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%(longdesc)s

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"""