Pay later option incorrectly shows as completed when combining membership and donation

Steps to reproduce:

Using demo server: https://civicrm.demo.civihosting.com

(I think the above server is CiviCRM 4.7)

Log in as demo user

Click menu Administer>CiviMember>Membership Types

Click "Add Membership Type"

Data Entry as follows:

Name = SFF Member

Membership Organisation = Default Organisation

Minimum Fee = 10

Financical Type = Member Dues

Membership Type Duration Unit = 1 year

Membership type plan = Rolling

Click "Save"

Menu "Contributions>New Contribution page"

Title = SFF Members

Financial Type = Member Dues

Goal amount and start and end dates = blank

Click "Continue"

NOW in Contribution amounts section

Tick "Pay later option"

Enter some text in the "Pay Later instructions"

Tick "Contribution Amounts section enabled"

Enter text in "Contribution Amounts Label"

Tick "Allow other amounts"

Enter Minumum amount = 5

Add an option in "Fixed Contribtion options"

Eg. Contribution Label="Help CRM", Amount=200

Click "Save and Next" to go to " Membership Signup and Renewal"

Tick "Membership section enabled?"

Type "Title - New Membership" = New SFF Membership

Type "Title - Renewals" = Renew SFF Membership

Under "Membership Types" select "SFF Member" as default

Tick "Require Membership Signup"

Tick "Separate Membership Payment"

Click "Save and Next"

On Thank-you and Receipting (SFF Members) page

"Thank-you Page Title" = Thanks for joining

Click "Save and Done"

We are now back at "Manage Contribution Pages"

By "SFF Members" click "Links">"Live Page"

Under "Additional Contribution" select "No Thank you"

(The only payment option should be the pay later option of "I will send payment by check")

Click "Confirm Contribution"

Click "Continue"

Click menu "Contributions>Dashboard"

The new member payment shows with a status of completed. It should be "Pending."

Now try this:

Click menu "Contributions>Manage Contribution Pages"

By "SFF Members" click "Links">"Live Page"

Under "Additional Contribution" select "SFF Donation - $200"

(The only payment option should be the pay later option of "I will send payment by check")

Click "Confirm Contribution"

Click "Continue"

An error comes up in a red block:

-------------------
Notice: Undefined index: payment_instrument_id in CRM_Contribute_Form_Contribution_Confirm::processFormContribution() (line 946 of /home/galleryr/www/civicrm.demo/sites/all/modules/civicrm/CRM/Contribute/Form/Contribution/Confirm.php).
------------------------

Click menu "Contributions>Dashboard"

The new member payment shows as "Pending" as they should be.

I tried this process on a server running CiviCRM 4.6 and it seemed to work correctly.

So this appears to be a bug introduced in 4.7

Cheers,

Norman Cates