Merge branch 'jk/log-fp-implies-m'

"git log --first-parent -p" showed patches only for single-parent
commits on the first-parent chain; the "--first-parent" option has
been made to imply "-m".  Use "--no-diff-merges" to restore the
previous behaviour to omit patches for merge commits.

* jk/log-fp-implies-m:
  doc/git-log: clarify handling of merge commit diffs
  doc/git-log: move "-t" into diff-options list
  doc/git-log: drop "-r" diff option
  doc/git-log: move "Diff Formatting" from rev-list-options
  log: enable "-m" automatically with "--first-parent"
  revision: add "--no-diff-merges" option to counteract "-m"
  log: drop "--cc implies -m" logic

Documentation/rev-list-options.txt

@@ -1116,48 +1116,3 @@ ifdef::git-rev-list[]
 	by a tab.
 endif::git-rev-list[]
 endif::git-shortlog[]
-
-ifndef::git-shortlog[]
-ifndef::git-rev-list[]
-Diff Formatting
-~~~~~~~~~~~~~~~
-
-Listed below are options that control the formatting of diff output.
-Some of them are specific to linkgit:git-rev-list[1], however other diff
-options may be given. See linkgit:git-diff-files[1] for more options.
-
--c::
-	With this option, diff output for a merge commit
-	shows the differences from each of the parents to the merge result
-	simultaneously instead of showing pairwise diff between a parent
-	and the result one at a time. Furthermore, it lists only files
-	which were modified from all parents.
-
---cc::
-	This flag implies the `-c` option and further compresses the
-	patch output by omitting uninteresting hunks whose contents in
-	the parents have only two variants and the merge result picks
-	one of them without modification.
-
---combined-all-paths::
-	This flag causes combined diffs (used for merge commits) to
-	list the name of the file from all parents.  It thus only has
-	effect when -c or --cc are specified, and is likely only
-	useful if filename changes are detected (i.e. when either
-	rename or copy detection have been requested).
-
--m::
-	This flag makes the merge commits show the full diff like
-	regular commits; for each merge parent, a separate log entry
-	and diff is generated. An exception is that only diff against
-	the first parent is shown when `--first-parent` option is given;
-	in that case, the output represents the changes the merge
-	brought _into_ the then-current branch.
-
--r::
-	Show recursive diffs.
-
--t::
-	Show the tree objects in the diff output. This implies `-r`.
-endif::git-rev-list[]
-endif::git-shortlog[]