Today, I put text to a page by my bot. pywikibot.showDiff() shows clearly that text is removed from previous revision for 2 lines and code returns from put() also indicate that putting succeeds
(302, 'OK', {u'pageid': ..., u'title': u'...', u'newtimestamp': u'...', u'contentmodel': u'wikitext', u'result': u'Success', u'oldrevid': ..., u'newrevid': ...})
However, actually the text isn't changed! History page shows me that the text is added 1 byte (or sometimes o byte), but the content and its previous version are really the same.