• Fix compatibility with newer scikit-learn. (#6555)
• Fix wrong best_ntree_limit in multi-class. (#6569)
• Ensure that Rabit can be compiled on Solaris (#6578)
• Fix best_ntree_limit for linear and dart. (#6579)
• Remove duplicated DMatrix creation in scikit-learn interface. (#6592)
• Fix evals_result in XGBRanker. (##6594)