merge(3p/git): Merge git subtree at v2.29.2 r/1890

This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb

2 files changed, 52 insertions, 0 deletions

diff --git a/third_party/git/negotiator/noop.c b/third_party/git/negotiator/noop.c
new file mode 100644
index 000000000000..60569b83501a
--- /dev/null
+++ b/third_party/git/negotiator/noop.c
@@ -0,0 +1,44 @@
+#include "cache.h"
+#include "noop.h"
+#include "../commit.h"
+#include "../fetch-negotiator.h"
+
+static void known_common(struct fetch_negotiator *n, struct commit *c)
+{
+	/* do nothing */
+}
+
+static void add_tip(struct fetch_negotiator *n, struct commit *c)
+{
+	/* do nothing */
+}
+
+static const struct object_id *next(struct fetch_negotiator *n)
+{
+	return NULL;
+}
+
+static int ack(struct fetch_negotiator *n, struct commit *c)
+{
+	/*
+	 * This negotiator does not emit any commits, so there is no commit to
+	 * be acknowledged. If there is any ack, there is a bug.
+	 */
+	BUG("ack with noop negotiator, which does not emit any commits");
+	return 0;
+}
+
+static void release(struct fetch_negotiator *n)
+{
+	/* nothing to release */
+}
+
+void noop_negotiator_init(struct fetch_negotiator *negotiator)
+{
+	negotiator->known_common = known_common;
+	negotiator->add_tip = add_tip;
+	negotiator->next = next;
+	negotiator->ack = ack;
+	negotiator->release = release;
+	negotiator->data = NULL;
+}
diff --git a/third_party/git/negotiator/noop.h b/third_party/git/negotiator/noop.h
new file mode 100644
index 000000000000..2b4ec5d07a27
--- /dev/null
+++ b/third_party/git/negotiator/noop.h
@@ -0,0 +1,8 @@
+#ifndef NEGOTIATOR_NOOP_H
+#define NEGOTIATOR_NOOP_H
+
+struct fetch_negotiator;
+
+void noop_negotiator_init(struct fetch_negotiator *negotiator);
+
+#endif