t7700: replace egrep with grep

The egrep expressions in this test suite were of the form `^$variable`.
Although egrep works just fine, it's overkill since we're not using any
extended regex. Replace egrep invocations with grep so that we aren't
swatting flies with a sledgehammer.

Signed-off-by: Denton Liu <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Denton-L

t/t7700-repack.sh

@@ -30,7 +30,7 @@ test_has_duplicate_object () {
 		idx=$(basename $p)
 		test "pack-$packsha1.idx" = "$idx" && continue
 		git verify-pack -v $p >packlist || return $?
-		if egrep "^$objsha1" packlist
+		if grep "^$objsha1" packlist
 		then
 			found_duplicate_object=true
 			echo "DUPLICATE OBJECT FOUND"
@@ -135,7 +135,7 @@ test_expect_success 'packed unreachable obs in alternate ODB are not loosened' '
 	rm -f .git/objects/pack/* &&
 	mv pack-* .git/objects/pack/ &&
 	test 0 = $(git verify-pack -v -- .git/objects/pack/*.idx |
-		egrep "^$csha1 " | sort | uniq | wc -l) &&
+		grep "^$csha1 " | sort | uniq | wc -l) &&
 	echo >.git/objects/info/alternates &&
 	test_must_fail git show $csha1
 '
@@ -152,7 +152,7 @@ test_expect_success 'local packed unreachable obs that exist in alternate ODB ar
 	rm -f .git/objects/pack/* &&
 	mv pack-* .git/objects/pack/ &&
 	test 0 = $(git verify-pack -v -- .git/objects/pack/*.idx |
-		egrep "^$csha1 " | sort | uniq | wc -l) &&
+		grep "^$csha1 " | sort | uniq | wc -l) &&
 	echo >.git/objects/info/alternates &&
 	test_must_fail git show $csha1
 '