[PATCH 3/6] fsmonitor: Update helper tool, now that flags are filled later

[Alex Vandiver <alexmv@dropbox.com>]

dd9005a0a ("fsmonitor: delay updating state until after split index is
merged", 2017-10-27) began deferring the setting of the
CE_FSMONITOR_VALID flag until later, such that do_read_index() does
not perform those steps.  This means that t/helper/test-dump-fsmonitor
showed all bits as always unset.

Load the index using read_index_from(), which is aware of split
indexes and later fsmonitor ewah inflation, but ensure that we do not
add or remove it, by setting the value to "keep".

Signed-off-by: Alex Vandiver <alexmv@dropbox.com>
---
 config.c                       | 9 +++++++--
 t/helper/test-dump-fsmonitor.c | 4 +++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/config.c b/config.c
index e617c2018..7c6ed888e 100644
--- a/config.c
+++ b/config.c
@@ -2174,8 +2174,13 @@ int git_config_get_fsmonitor(void)
 	if (core_fsmonitor && !*core_fsmonitor)
 		core_fsmonitor = NULL;
 
-	if (core_fsmonitor)
-		return 1;
+
+	if (core_fsmonitor) {
+		if (!strcasecmp(core_fsmonitor, "keep"))
+			return -1;
+		else
+			return 1;
+	}
 
 	return 0;
 }
diff --git a/t/helper/test-dump-fsmonitor.c b/t/helper/test-dump-fsmonitor.c
index ad452707e..48c4bab0b 100644
--- a/t/helper/test-dump-fsmonitor.c
+++ b/t/helper/test-dump-fsmonitor.c
@@ -1,12 +1,14 @@
 #include "cache.h"
+#include "config.h"
 
 int cmd_main(int ac, const char **av)
 {
 	struct index_state *istate = &the_index;
 	int i;
 
+	git_config_push_parameter("core.fsmonitor=keep");
 	setup_git_directory();
-	if (do_read_index(istate, get_index_file(), 0) < 0)
+	if (read_index_from(istate, get_index_file()) < 0)
 		die("unable to read index file");
 	if (!istate->fsmonitor_last_update) {
 		printf("no fsmonitor\n");
-- 
2.15.1.31.gddce0adfe