This branch is now 2.1.8-bleeding
For customer search, join once. Performance increase.
Backorders at variation level

Added a new select metabox for variations allowing users to control
backorders at the variation level.
Might need more testing.
ref: #5351
Template cleanup
Print notices in view order template Closes #5348
Add action filter in inventory product data

Allows plugins to add meta fields after stock status/backorders even if woocommerce_manage_stock is turned off.
Another action hook in Inventory product data tab

allow plugins to create a new options_group in this tab
Merge pull request #5353 from tamarazuk/backorder-variations

Backorders at variation level
Merge pull request #5384 from tamarazuk/patch-1

Add action filter in inventory product data
Update class-wc-checkout.php

Recalculating the cart totals, in the event a user registers during checkout and in doing so qualifies for any discounts
Update comment to reflect that parameter template_name for wc_get/locate_template() only accepts strings
Fixes #5389
Merge pull request #5388 from mkayan-wakefly/patch-1

RE issue: #5387 - Update class-wc-checkout.php
Merge pull request #5390 from jjeaton/locate-template-comment

Update comment to reflect that parameter template_name for wc_get/locate...
Prevent duplicate admin menu items Closes #5380
Update REST API documentation link
Update class-wc-frontend-scripts.php

See also https://github.com/bassjobsen/wp-defer-loading/issues/14 prettyPhoto-init is not only dependent of jquery, but also of prettyPhoto. The dependency of prettyPhoto is not set.
removed wc_clean/sanitize_text_field not needed. handled by wp core functions fixes #5318
added method to stop save duplicate sku in quick edit
fixed coding standards in includes/admin/post-types/class-wc-admin-cpt-product.php
Removes unused block and var.

There's duplicate block that does the same thing, but assigning to different variable.
On the end only the last variable is used, which is `$username`.