Merge branch 'jk/core-comment-string'

core.commentChar used to be limited to a single byte, but has been
updated to allow an arbitrary multi-byte sequence.

* jk/core-comment-string:
  config: add core.commentString
  config: allow multi-byte core.commentChar
  environment: drop comment_line_char compatibility macro
  wt-status: drop custom comment-char stringification
  sequencer: handle multi-byte comment characters when writing todo list
  find multi-byte comment chars in unterminated buffers
  find multi-byte comment chars in NUL-terminated strings
  prefer comment_line_str to comment_line_char for printing
  strbuf: accept a comment string for strbuf_add_commented_lines()
  strbuf: accept a comment string for strbuf_commented_addf()
  strbuf: accept a comment string for strbuf_stripspace()
  environment: store comment_line_char as a string
  strbuf: avoid shadowing global comment_line_char name
  commit: refactor base-case of adjust_comment_line_char()
  strbuf: avoid static variables in strbuf_add_commented_lines()
  strbuf: simplify comment-handling in add_lines() helper
  config: forbid newline as core.commentChar

commit.c

@@ -1928,7 +1928,8 @@ size_t ignored_log_message_bytes(const char *buf, size_t len)
 		else
 			next_line++;
 
-		if (buf[bol] == comment_line_char || buf[bol] == '\n') {
+		if (starts_with_mem(buf + bol, cutoff - bol, comment_line_str) ||
+		    buf[bol] == '\n') {
 			/* is this the first of the run of comments? */
 			if (!boc)
 				boc = bol;