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

1 files changed, 16 insertions, 6 deletions

diff --git a/third_party/git/trace.c b/third_party/git/trace.c
index fa4a2e7120..f726686fd9 100644
--- a/third_party/git/trace.c
+++ b/third_party/git/trace.c
@@ -29,7 +29,7 @@ struct trace_key trace_perf_key = TRACE_KEY_INIT(PERFORMANCE);
 struct trace_key trace_setup_key = TRACE_KEY_INIT(SETUP);
 
 /* Get a trace file descriptor from "key" env variable. */
-static int get_trace_fd(struct trace_key *key)
+static int get_trace_fd(struct trace_key *key, const char *override_envvar)
 {
 	const char *trace;
 
@@ -37,7 +37,7 @@ static int get_trace_fd(struct trace_key *key)
 	if (key->initialized)
 		return key->fd;
 
-	trace = getenv(key->key);
+	trace = override_envvar ? override_envvar : getenv(key->key);
 
 	if (!trace || !strcmp(trace, "") ||
 	    !strcmp(trace, "0") || !strcasecmp(trace, "false"))
@@ -68,6 +68,18 @@ static int get_trace_fd(struct trace_key *key)
 	return key->fd;
 }
 
+void trace_override_envvar(struct trace_key *key, const char *value)
+{
+	trace_disable(key);
+	key->initialized = 0;
+
+	/*
+	 * Invoke get_trace_fd() to initialize key using the given value
+	 * instead of the value of the environment variable.
+	 */
+	get_trace_fd(key, value);
+}
+
 void trace_disable(struct trace_key *key)
 {
 	if (key->need_close)
@@ -88,8 +100,6 @@ static int prepare_trace_line(const char *file, int line,
 	if (!trace_want(key))
 		return 0;
 
-	set_try_to_free_routine(NULL);	/* is never reset */
-
 	/* unit tests may want to disable additional trace output */
 	if (trace_want(&trace_bare))
 		return 1;
@@ -114,7 +124,7 @@ static int prepare_trace_line(const char *file, int line,
 
 static void trace_write(struct trace_key *key, const void *buf, unsigned len)
 {
-	if (write_in_full(get_trace_fd(key), buf, len) < 0) {
+	if (write_in_full(get_trace_fd(key, NULL), buf, len) < 0) {
 		warning("unable to write trace for %s: %s",
 			key->key, strerror(errno));
 		trace_disable(key);
@@ -385,7 +395,7 @@ void trace_repo_setup(const char *prefix)
 
 int trace_want(struct trace_key *key)
 {
-	return !!get_trace_fd(key);
+	return !!get_trace_fd(key, NULL);
 }
 
 #if defined(HAVE_CLOCK_GETTIME) && defined(HAVE_CLOCK_MONOTONIC)