A DESCRIPTION OF THE PROBLEM :
The following ant target, which attempts to delete files that are 3 days old (or older), throws an error under Java 9 and 10:

<target name="-delete-old-log-files">
  <tstamp>
    <format property="old.file.stamp"
            pattern="MM/dd/yyyy hh:mm a"
            locale="en,UK"
            offset="-3"
            unit="day"/>
  </tstamp>
  <delete>
    <fileset dir="${logging.dir}" includes="*/**">
      <date datetime="${old.file.stamp}" when="before"/>
    </fileset>
  </delete>
</target>

Error thrown: "Date Cannot be parsed correctly. It should be in MM/DD/YYYY HH:MM AM_PM format"

There are no issues when executing the same ant target under Java 8.

REGRESSION : Last worked in version 8u172

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Build the Java program below with 1.8.0_172 and run under 1.8.0_172 and 10.0.1.




EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
long value
ACTUAL -
Exception in thread "main" java.text.ParseException: Unparseable date: "07/06/2018 10:56 AM"
at java.base/java.text.DateFormat.parse(DateFormat.java:395)
at Main.main(Main.java:10)

---------- BEGIN SOURCE ----------
import java.text.DateFormat;
import java.text.ParseException;
import java.util.Locale;

public class Main {

    public static void main(final String[] args) throws ParseException {

        final DateFormat df = DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.SHORT, Locale.US);
        final long millis = df.parse("07/06/2018 10:56 AM").getTime();
        System.out.println(millis);
    }
}

---------- END SOURCE ----------

FREQUENCY : always