You can clone with
Invalid CSS after "...nd-image:url(""": expected ")", was "/assets/twitter..."
So, I switch back to old version'2.0.7'
No error occurred.
Same error. Went back to 2.0.8.
Same error, also went back to 2.0.8
This change looks related: 5269f00
I hit with this error before and it seem related to asset-path takes two variable
@iconSpritePath: asset-path('twitter/bootstrap/glyphicons-halflings.png', image);
@iconWhiteSpritePath: asset-path('twitter/bootstrap/glyphicons-halflings-white.png', image);
This should fix the problem
@ano1chan solution worked for me.