fixup! fsmonitor: reintroduce core.useBuiltinFSMonitor

Under certain (not quite easy to force, apparently) circumstances, a Git
process that just warned about the deprecated config setting will spawn
another Git process that then _also_ warns about that config setting.

Let's try to tone that down by setting an environment variable that
indicates that this process and all of its children no longer need to
tell the user about this deprecation.

Note: This patch does not help in situations where, say, scripts call
Git multiple times and each of those times Git prints this deprecation
notice. It is unclear whether we can do anything about this because
those Git processes would have to signal to their _parent_ process that
the advice was already provided.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

fsmonitor-settings.c

@@ -59,9 +59,12 @@ static int check_deprecated_builtin_config(struct repository *r)
 	 * the check resulted the config being set by this (deprecated) setting.
 	 */
 	if(!repo_config_get_bool(r, "core.useBuiltinFSMonitor", &core_use_builtin_fsmonitor)) {
-		advise_if_enabled(ADVICE_USE_CORE_FSMONITOR_CONFIG,
-				  _("core.useBuiltinFSMonitor will be deprecated "
-				    "soon; use core.fsmonitor instead"));
+		if (!git_env_bool("GIT_SUPPRESS_USEBUILTINFSMONITOR_ADVICE", 0)) {
+			advise_if_enabled(ADVICE_USE_CORE_FSMONITOR_CONFIG,
+					  _("core.useBuiltinFSMonitor will be deprecated "
+					    "soon; use core.fsmonitor instead"));
+			setenv("GIT_SUPPRESS_USEBUILTINFSMONITOR_ADVICE", "1", 1);
+		}
 		if (core_use_builtin_fsmonitor) {
 			fsm_settings__set_ipc(r);
 			return 1;