Merge branch 'bc/commit-complete-lines-given-via-m-option'

'git commit -m "$str"' when $str was already terminated with a LF now avoids adding an extra LF to the message. * bc/commit-complete-lines-given-via-m-option: Documentation/git-commit.txt: rework the --cleanup section git-commit: only append a newline to -m mesg if necessary t7502: demonstrate breakage with a commit message with trailing newlines t/t7502: compare entire commit message with what was expected