Merge branch 'jk/warn-author-committer-after-commit'

* jk/warn-author-committer-after-commit:
  user_ident_sufficiently_given(): refactor the logic to be usable from elsewhere
  commit.c::print_summary: do not release the format string too early
  commit: allow suppression of implicit identity advice
  commit: show interesting ident information in summary
  strbuf: add strbuf_addbuf_percentquote
  strbuf_expand: convert "%%" to "%"

Conflicts:
	builtin-commit.c
	ident.c

Documentation/technical/api-strbuf.txt

@@ -199,6 +199,10 @@ character if the letter `n` appears after a `%`.  The function returns
 the length of the placeholder recognized and `strbuf_expand()` skips
 over it.
 +
+The format `%%` is automatically expanded to a single `%` as a quoting
+mechanism; callers do not need to handle the `%` placeholder themselves,
+and the callback function will not be invoked for this placeholder.
++
 All other characters (non-percent and not skipped ones) are copied
 verbatim to the strbuf.  If the callback returned zero, meaning that the
 placeholder is unknown, then the percent sign is copied, too.
@@ -214,6 +218,13 @@ which can be used by the programmer of the callback as she sees fit.
 	placeholder and replacement string.  The array needs to be
 	terminated by an entry with placeholder set to NULL.
 
+`strbuf_addbuf_percentquote`::
+
+	Append the contents of one strbuf to another, quoting any
+	percent signs ("%") into double-percents ("%%") in the
+	destination. This is useful for literal data to be fed to either
+	strbuf_expand or to the *printf family of functions.
+
 `strbuf_addf`::
 
 	Add a formatted string to the buffer.