Update test order to avoid spurious test failures due to timing.

copy_file_tests with copy_options::update_existing used to fail sometimes,
when the last modification timestamps on the test files were close enough.
Run the tests after a pause to make sure the timestamps are far enough apart.

test/operations_test.cpp

@@ -1929,30 +1929,31 @@ void copy_file_tests(const fs::path& f1x, const fs::path& d1x)
     verify_file(d1x / "f2-non-existing", "file-f1");
     fs::remove(d1x / "f2-non-existing");
 
+    // Sleep for a while so that the last modify time is more recent for new files
+#if defined(BOOST_POSIX_API)
+    sleep(2);
+#else
+    Sleep(2000);
+#endif
+
+    create_file(d1x / "f2-more-recent", "x");
+    BOOST_TEST_EQ(fs::file_size(d1x / "f2-more-recent"), 1U);
+
     file_copied = false;
     copy_ex_ok = true;
     try
     {
-        file_copied = fs::copy_file(f1x, d1x / "f2", fs::copy_options::update_existing);
+        file_copied = fs::copy_file(d1x / "f2", d1x / "f2-more-recent", fs::copy_options::update_existing);
     }
     catch (const fs::filesystem_error&)
     {
         copy_ex_ok = false;
     }
     BOOST_TEST(copy_ex_ok);
     BOOST_TEST(!file_copied);
-    BOOST_TEST_EQ(fs::file_size(d1x / "f2"), 10U);
-    verify_file(d1x / "f2", "1234567890");
-
-    // Sleep for a while so that the last modify time is more recent for new files
-#if defined(BOOST_POSIX_API)
-    sleep(2);
-#else
-    Sleep(2000);
-#endif
-
-    create_file(d1x / "f2-more-recent", "x");
     BOOST_TEST_EQ(fs::file_size(d1x / "f2-more-recent"), 1U);
+    verify_file(d1x / "f2-more-recent", "x");
+
     file_copied = false;
     copy_ex_ok = true;
     try