img test: set old timestamp on source file that will change

This is so that the test will pass even if it takes less than 1 second.

1 files changed, 1 insertions, 0 deletions

diff --git a/t/img.t b/t/img.t
index 7e7753aab..7598dd9f0 100755
--- a/t/img.t
+++ b/t/img.t
@@ -55,6 +55,7 @@ $maybe_svg_img
 [[!img twopages.pdf size=16x pagenumber=1]]
 EOF
 );
+ok(utime(333333333, 333333333, "t/tmp/in/imgconversions.mdwn"));
 
 ok(! system("make -s ikiwiki.out"));