pkg install hangs

[S Crombie]

I am running Octave 5.1.0 in Windows 7 and trying to install the image
acquisition package but this always hangs and never completes.

I have used 

          pkg install -verbose image-acquisition-0.2.2.tar.gz

and I can see from the verbose output that the install is getting stuck
after the untar command.

Here is a segment from install.m which is used in the pkg process. I have
added in a couple of printf statements for debugging

        ## Uncompress the package.
        if (verbose)
          printf ("untar (%s, %s)\n", tgz, tmpdir);
        endif
        untar (tgz, tmpdir);
        if (verbose)
          printf ("untar completed");
        endif

        ## Get the name of the directories produced by tar.
        if (verbose)
          printf ("Getting directory list");
        endif
        
        [dirlist, err, msg] = readdir (tmpdir);

When I run the install it prints "untar completed" but never prints "Getting
directory list" although it looks to me as if these are consecutive items.

I would be grateful for any ideas as to why this is not working.

Thanks