Merge branch 'maint'

* maint: Better advice on using topic branches for kernel development Documentation: update implicit "--no-index" behavior in "git diff" Documentation: expand 'git diff' SEE ALSO section Documentation: diff can compare blobs Documentation: gitrevisions is in section 7 shell portability: no "export VAR=VAL" CodingGuidelines: reword parameter expansion section Documentation: update-index: -z applies also to --index-info Documentation: No argument of ALLOC_GROW should have side-effects