read-cache: use freshen_shared_index() in read_index_from()

This way a share index file will not be garbage collected if
we still read from an index it is based from.

As we need to read the current index before creating a new
one, the tests have to be adjusted, so that we don't expect
an old shared index file to be deleted right away when we
create a new one.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

read-cache.c

@@ -1727,6 +1727,7 @@ int read_index_from(struct index_state *istate, const char *path)
 		    base_sha1_hex, base_path,
 		    sha1_to_hex(split_index->base->sha1));
 
+	freshen_shared_index(base_sha1_hex, 0);
 	merge_base_index(istate);
 	post_read_index_from(istate);
 	return ret;

t/t1700-split-index.sh

@@ -313,30 +313,30 @@ test_expect_success 'check splitIndex.maxPercentChange set to 0' '
 test_expect_success 'shared index files expire after 2 weeks by default' '
 	: >ten &&
 	git update-index --add ten &&
-	test $(ls .git/sharedindex.* | wc -l) -gt 1 &&
+	test $(ls .git/sharedindex.* | wc -l) -gt 2 &&
 	just_under_2_weeks_ago=$((5-14*86400)) &&
 	test-chmtime =$just_under_2_weeks_ago .git/sharedindex.* &&
 	: >eleven &&
 	git update-index --add eleven &&
-	test $(ls .git/sharedindex.* | wc -l) -gt 1 &&
+	test $(ls .git/sharedindex.* | wc -l) -gt 2 &&
 	just_over_2_weeks_ago=$((-1-14*86400)) &&
 	test-chmtime =$just_over_2_weeks_ago .git/sharedindex.* &&
 	: >twelve &&
 	git update-index --add twelve &&
-	test $(ls .git/sharedindex.* | wc -l) = 1
+	test $(ls .git/sharedindex.* | wc -l) -le 2
 '
 
 test_expect_success 'check splitIndex.sharedIndexExpire set to 16 days' '
 	git config splitIndex.sharedIndexExpire "16.days.ago" &&
 	test-chmtime =$just_over_2_weeks_ago .git/sharedindex.* &&
 	: >thirteen &&
 	git update-index --add thirteen &&
-	test $(ls .git/sharedindex.* | wc -l) -gt 1 &&
+	test $(ls .git/sharedindex.* | wc -l) -gt 2 &&
 	just_over_16_days_ago=$((-1-16*86400)) &&
 	test-chmtime =$just_over_16_days_ago .git/sharedindex.* &&
 	: >fourteen &&
 	git update-index --add fourteen &&
-	test $(ls .git/sharedindex.* | wc -l) = 1
+	test $(ls .git/sharedindex.* | wc -l) -le 2
 '
 
 test_expect_success 'check splitIndex.sharedIndexExpire set to "never" and "now"' '
@@ -345,13 +345,13 @@ test_expect_success 'check splitIndex.sharedIndexExpire set to "never" and "now"
 	test-chmtime =$just_10_years_ago .git/sharedindex.* &&
 	: >fifteen &&
 	git update-index --add fifteen &&
-	test $(ls .git/sharedindex.* | wc -l) -gt 1 &&
+	test $(ls .git/sharedindex.* | wc -l) -gt 2 &&
 	git config splitIndex.sharedIndexExpire now &&
 	just_1_second_ago=-1 &&
 	test-chmtime =$just_1_second_ago .git/sharedindex.* &&
 	: >sixteen &&
 	git update-index --add sixteen &&
-	test $(ls .git/sharedindex.* | wc -l) = 1
+	test $(ls .git/sharedindex.* | wc -l) -le 2
 '
 
 test_done