git p4 test: refactor marshal_dump

This function will be useful in future tests.  Move it to
the git-p4 test library.  Let it accept an optional argument
to pick a certain marshaled object out of the input stream.

Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/lib-git-p4.sh

@@ -102,3 +102,16 @@ cleanup_git() {
 	rm -rf "$git" &&
 	mkdir "$git"
 }
+
+marshal_dump() {
+	what=$1 &&
+	line=${2:-1} &&
+	cat >"$TRASH_DIRECTORY/marshal-dump.py" <<-EOF &&
+	import marshal
+	import sys
+	for i in range($line):
+	    d = marshal.load(sys.stdin)
+	print d['$what']
+	EOF
+	"$PYTHON_PATH" "$TRASH_DIRECTORY/marshal-dump.py"
+}

t/t9800-git-p4-basic.sh

@@ -155,11 +155,6 @@ test_expect_success 'clone bare' '
 	)
 '
 
-marshal_dump() {
-	what=$1
-	"$PYTHON_PATH" -c 'import marshal, sys; d = marshal.load(sys.stdin); print d["'$what'"]'
-}
-
 # Sleep a bit so that the top-most p4 change did not happen "now".  Then
 # import the repo and make sure that the initial import has the same time
 # as the top-most change.