The key binding to “insert_snippet” command is broken in build 3114.
Here’s the corresponding key mapping:
{ "keys": ["ctrl+shift+w"], "command": "insert_snippet", "args": { "name": "Packages/XML/long-tag.sublime-snippet" } },
however since the new build there’s no XML subdir in Packages
The default keybindings have been correctly updated to use the Snippets subfolder - from Default (OSX).sublime-keymap { "keys": ["ctrl+shift+w"], "command": "insert_snippet", "args": { "name": "Packages/XML/Snippets/long-tag.sublime-snippet" } }, (at least on 3113.)
Thanks @kingkeith, but then where was this content before and how can I reinstate it? The path as defined may b e correct, but it does not exist and I’ve no idea what and how the content of long-tag.sublime-snippet was defined 
This snippet is defined in the built in XML Package - the github repo is the best place to see the history of the file https://github.com/sublimehq/Packages/blob/master/XML/Snippets/long-tag.sublime-snippet