revert(3p/git): Revert merge of git upstream at v2.26.2

This causes cgit to serve error pages, which is undesirable.

This reverts commit 5229c9b232, reversing
changes made to f2b211131f.

third_party/git/graph.h

@@ -2,103 +2,6 @@
 #define GRAPH_H
 #include "diff.h"
 
-/**
- * The graph API is used to draw a text-based representation of the commit
- * history. The API generates the graph in a line-by-line fashion.
- *
- * Calling sequence
- * ----------------
- *
- * - Create a `struct git_graph` by calling `graph_init()`.  When using the
- *   revision walking API, this is done automatically by `setup_revisions()` if
- *   the '--graph' option is supplied.
- *
- * - Use the revision walking API to walk through a group of contiguous commits.
- *   The `get_revision()` function automatically calls `graph_update()` each time
- *   it is invoked.
- *
- * - For each commit, call `graph_next_line()` repeatedly, until
- *   `graph_is_commit_finished()` returns non-zero.  Each call to
- *   `graph_next_line()` will output a single line of the graph.  The resulting
- *   lines will not contain any newlines.  `graph_next_line()` returns 1 if the
- *   resulting line contains the current commit, or 0 if this is merely a line
- *   needed to adjust the graph before or after the current commit.  This return
- *   value can be used to determine where to print the commit summary information
- *   alongside the graph output.
- *
- * Limitations
- * -----------
- * - Check the graph_update() function for its limitations.
- *
- * - The graph API does not currently support reverse commit ordering.  In
- *   order to implement reverse ordering, the graphing API needs an
- *   (efficient) mechanism to find the children of a commit.
- *
- * Sample usage
- * ------------
- *
- * ------------
- * struct commit *commit;
- * struct git_graph *graph = graph_init(opts);
- *
- * while ((commit = get_revision(opts)) != NULL) {
- * 	while (!graph_is_commit_finished(graph))
- * 	{
- * 		struct strbuf sb;
- * 		int is_commit_line;
- *
- * 		strbuf_init(&sb, 0);
- * 		is_commit_line = graph_next_line(graph, &sb);
- * 		fputs(sb.buf, stdout);
- *
- * 		if (is_commit_line)
- * 			log_tree_commit(opts, commit);
- * 		else
- * 			putchar(opts->diffopt.line_termination);
- * 	}
- * }
- * ------------
- * Sample output
- * -------------
- *
- * The following is an example of the output from the graph API.  This output does
- * not include any commit summary information--callers are responsible for
- * outputting that information, if desired.
- * ------------
- * *
- * *
- * *
- * |\
- * * |
- * | | *
- * | \ \
- * |  \ \
- * *-. \ \
- * |\ \ \ \
- * | | * | |
- * | | | | | *
- * | | | | | *
- * | | | | | *
- * | | | | | |\
- * | | | | | | *
- * | * | | | | |
- * | | | | | *  \
- * | | | | | |\  |
- * | | | | * | | |
- * | | | | * | | |
- * * | | | | | | |
- * | |/ / / / / /
- * |/| / / / / /
- * * | | | | | |
- * |/ / / / / /
- * * | | | | |
- * | | | | | *
- * | | | | |/
- * | | | | *
- * ------------
- *
- */
-
 /* A graph is a pointer to this opaque structure */
 struct git_graph;
 
@@ -147,21 +50,6 @@ struct git_graph *graph_init(struct rev_info *opt);
  * If graph_update() is called before graph_is_commit_finished() returns 1,
  * the next call to graph_next_line() will output an ellipsis ("...")
  * to indicate that a portion of the graph is missing.
- *
- * Limitations:
- * -----------
- *
- * - `graph_update()` must be called with commits in topological order.  It should
- *   not be called on a commit if it has already been invoked with an ancestor of
- *   that commit, or the graph output will be incorrect.
- *
- * - `graph_update()` must be called on a contiguous group of commits.  If
- *   `graph_update()` is called on a particular commit, it should later be called
- *   on all parents of that commit.  Parents must not be skipped, or the graph
- *   output will appear incorrect.
- *
- * - `graph_update()` may be used on a pruned set of commits only if the parent list
- *   has been rewritten so as to include only ancestors from the pruned set.
  */
 void graph_update(struct git_graph *graph, struct commit *commit);
 
@@ -174,10 +62,6 @@ void graph_update(struct git_graph *graph, struct commit *commit);
  * for this commit.  If 0 is returned, graph_next_line() may still be
  * called without calling graph_update(), and it will merely output
  * appropriate "vertical padding" in the graph.
- *
- * If `graph_update()` is called before all lines for the current commit have
- * been printed, the next call to `graph_next_line()` will output an ellipsis,
- * to indicate that a portion of the graph was omitted.
  */
 int graph_is_commit_finished(struct git_graph const *graph);
 
@@ -228,7 +112,6 @@ void graph_show_padding(struct git_graph *graph);
 /*
  * If the graph is non-NULL, print the rest of the history graph for this
  * commit to stdout.  Does not print a terminating newline on the last line.
- * Returns 1 if output was printed, and 0 if no output was necessary.
  */
 int graph_show_remainder(struct git_graph *graph);
 
@@ -238,10 +121,6 @@ int graph_show_remainder(struct git_graph *graph);
  * This is similar to graph_show_strbuf(), but it always prints the
  * remainder of the graph.
  *
- * It is better than directly calling `graph_show_strbuf()` followed by
- * `graph_show_remainder()` since it properly handles buffers that do not end in
- * a terminating newline.
- *
  * If the strbuf ends with a newline, the output printed by
  * graph_show_commit_msg() will end with a newline.  If the strbuf is
  * missing a terminating newline (including if it is empty), the output