Add test for files that start with /dev/null

Author: Leonidas-from-XIV

test/test.ml

@@ -880,6 +880,16 @@ let busybox_diff_quotes = {|\
 let busybox_diff_quotes =
   operations [Patch.Edit ({|foo "bar" baz|}, {|foo bar "baz"|})] busybox_diff_quotes
 
+let dev_null_like = {|\
+--- /dev/null_but_actually_not
++++ b
+@@ -0,0 +1 @@
++foo
+|}
+
+let dev_null_like =
+  operations [Patch.Edit ("/dev/null_but_actually_not", "b")] dev_null_like
+
 let filename_diffs =
   [
     "unified diff with spaces", `Quick, unified_diff_spaces;
@@ -888,6 +898,7 @@ let filename_diffs =
     "unified diff with quotes", `Quick, unified_diff_quotes;
     "git diff with quotes", `Quick, git_diff_quotes;
     "busybox diff with quotes", `Quick, busybox_diff_quotes;
+    "file that looks like /dev/null", `Quick, dev_null_like;
   ]
 
 let tests = [