The following line references m-tweaks.js
https://github.com/DSpace/DSpace/blob/master/dspace-xmlui/src/main/webapp/themes/mobile/mobile.xsl#L141 however the file is not in github.
The reference was added here: https://github.com/DSpace/DSpace/commit/b08132f5de64b22c37ef013e221532fb40af104a
The file is available here: http://sc.lib.muohio.edu/themes/mobile/lib/m-tweaks.js
However, it looks like that file is customized for Miami University Libraries, so it may just need to be removed from the mobile.xsl?