Version 3.1.0 corrupting sourceURL index maps and producing broken javascript

[longhotsummer]

Version 3.1.0 of django-pipeline looks like it is producing JS which isn't valid.

My input JS file has code like this (initial contents of eval() removed for simplicity):

eval("... return range;\n}\n//# sourceMappingURL=index.js.map\n\n//# sourceURL=webpack://indigo/./node_modules/dom-anchor-text-position/lib/index.js?");

That is being transformed by django-pipeline into this (note the /# sourceURL at the end should be //# but is now /#):

eval("... return range;\n}\n//# sourceMappingURL=lib/index.js.map\n\n/# sourceURL=webpack:/indigo/node_modules/dom-anchor-text-position/lib/index.js?");

The problem is that /# is now interpreted as a regular expression, not as a comment, which causes the call to eval() to fail, because it's not a valid regex:

/# sourceURL=webpack:/indigo/node_modules/dom-anchor-text-position/lib/index.js?

Reverting to 3.0.0 fixes the problem.

• Here is my input file: https://github.com/laws-africa/indigo/blob/master/indigo_app/static/lib/external-imports.js
• Here is my pipeline config: https://github.com/laws-africa/indigo/blob/master/indigo/settings.py#L288