more war on "sleep" in tests

Two more tests that sleep only to waste tick can be converted to use
test_tick and take expiry parameters relative to $test_tick.  The basic
idea is to replace "sleep 1" with "test_tick" to cause the "time" to pass.

These tests are interested in expiring things with "now" as the timestamp,
soo use a timestamp relative to $test_tick to give them more stability and
reproducibility.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t7700-repack.sh

@@ -8,6 +8,7 @@ test_expect_success 'objects in packs marked .keep are not repacked' '
 	echo content1 > file1 &&
 	echo content2 > file2 &&
 	git add . &&
+	test_tick &&
 	git commit -m initial_commit &&
 	# Create two packs
 	# The first pack will contain all of the objects except one
@@ -40,6 +41,7 @@ test_expect_success 'loose objects in alternate ODB are not repacked' '
 	echo content3 > file3 &&
 	objsha1=$(GIT_OBJECT_DIRECTORY=alt_objects git hash-object -w file3) &&
 	git add file3 &&
+	test_tick &&
 	git commit -m commit_file3 &&
 	git repack -a -d -l &&
 	git prune-packed &&
@@ -73,6 +75,7 @@ test_expect_success 'packed obs in alt ODB are repacked when local repo has pack
 	rm -f .git/objects/pack/* &&
 	echo new_content >> file1 &&
 	git add file1 &&
+	test_tick &&
 	git commit -m more_content &&
 	git repack &&
 	git repack -a -d &&
@@ -118,8 +121,8 @@ test_expect_success 'packed unreachable obs in alternate ODB are not loosened' '
 	mv .git/objects/pack/* alt_objects/pack/ &&
 	csha1=$(git rev-parse HEAD^{commit}) &&
 	git reset --hard HEAD^ &&
-	sleep 1 &&
-	git reflog expire --expire=now --expire-unreachable=now --all &&
+	test_tick &&
+	git reflog expire --expire=$test_tick --expire-unreachable=$test_tick --all &&
 	# The pack-objects call on the next line is equivalent to
 	# git repack -A -d without the call to prune-packed
 	git pack-objects --honor-pack-keep --non-empty --all --reflog \
@@ -156,7 +159,7 @@ test_expect_success 'objects made unreachable by grafts only are kept' '
 	H1=$(git rev-parse HEAD^) &&
 	H2=$(git rev-parse HEAD^^) &&
 	echo "$H0 $H2" > .git/info/grafts &&
-	git reflog expire --expire=now --expire-unreachable=now --all &&
+	git reflog expire --expire=$test_tick --expire-unreachable=$test_tick --all &&
 	git repack -a -d &&
 	git cat-file -t $H1
 	'

t/t7701-repack-unpack-unreachable.sh

@@ -11,17 +11,20 @@ tsha1=
 test_expect_success '-A with -d option leaves unreachable objects unpacked' '
 	echo content > file1 &&
 	git add . &&
+	test_tick &&
 	git commit -m initial_commit &&
 	# create a transient branch with unique content
 	git checkout -b transient_branch &&
 	echo more content >> file1 &&
 	# record the objects created in the database for file, commit, tree
 	fsha1=$(git hash-object file1) &&
+	test_tick &&
 	git commit -a -m more_content &&
 	csha1=$(git rev-parse HEAD^{commit}) &&
 	tsha1=$(git rev-parse HEAD^{tree}) &&
 	git checkout master &&
 	echo even more content >> file1 &&
+	test_tick &&
 	git commit -a -m even_more_content &&
 	# delete the transient branch
 	git branch -D transient_branch &&
@@ -34,9 +37,11 @@ test_expect_success '-A with -d option leaves unreachable objects unpacked' '
 	git show $fsha1 &&
 	git show $csha1 &&
 	git show $tsha1 &&
-	# now expire the reflog
-	sleep 1 &&
-	git reflog expire --expire-unreachable=now --all &&
+	# now expire the reflog, while keeping reachable ones but expiring
+	# unreachables immediately
+	test_tick &&
+	sometimeago=$(( $test_tick - 10000 )) &&
+	git reflog expire --expire=$sometimeago --expire-unreachable=$test_tick --all &&
 	# and repack
 	git repack -A -d -l &&
 	# verify objects are retained unpacked
@@ -71,7 +76,7 @@ test_expect_success '-A without -d option leaves unreachable objects packed' '
 	test 1 = $(ls -1 .git/objects/pack/pack-*.pack | wc -l) &&
 	packfile=$(ls .git/objects/pack/pack-*.pack) &&
 	git branch -D transient_branch &&
-	sleep 1 &&
+	test_tick &&
 	git repack -A -l &&
 	test ! -f "$fsha1path" &&
 	test ! -f "$csha1path" &&