Phing - CopyTask is executing before ExecTask is complete?

Okay, I’m new to Phing, so I haven’t quite figured out the proper way to debug it. Here is what I think is happening. I have two exec tasks that package two chrome extensions, the I have a mkdir task followed by a copy task.

Both exec tasks are completing successfully, but the copy task is only finding 1 file to copy…

        <exec command="&quot;${chrome.exe}&quot; --pack-extension=&quot;${chrome.source}my_custom_css&quot; --pack-extension-key=&quot;${chrome.source}my_custom_css.pem&quot;" dir="." logoutput="true" checkreturn="true" />
        <exec command="&quot;${chrome.exe}&quot; --pack-extension=&quot;${chrome.source}my_tools&quot; --pack-extension-key=&quot;${chrome.source}my_tools.pem&quot;" dir="." logoutput="true" checkreturn="true" />
        <mkdir dir="build/chrome/" />
        <copy todir="build/chrome/">
            <fileset dir="chrome/">
                <include name="my_tools.crx" />
                <include name="my_custom_css.crx" />
            </fileset>
        </copy>
        <delete file="chrome/my_tools.crx"/>
        <delete file="chrome/my_custom_css.crx"/>

The delete tasks successfully delete both files, so now my question. How do I get the copy command to wait for the second exec to complete?

I added the checkreturn=“true” but that didn’t do what I had hoped, so it seems Chrome is throwing these processes into a background process and returning 0 immediately to the ExecTask.

Thoughts?