Bug overview description.
Searching with multiple source metatags will only use the last one entered, or in the event of ~source:, absolutely no results will be returned, even if the search would return results without using source: metatags.

What part(s) of the site page(s) are affected?
Posts page.

What is the expected behavior?
Posts that match every source metatag entered will be returned. Searching with ~source will return posts that match at least one of the provided strings.

What actual behavior is given instead?
Results are returned as if only the last source: metatag was entered. Searching with ~source returns no results ever.

Time of incident (if applicable).
Can you reproduce the bug every time?
What steps did you take to replicate this bug?
This can be reproduced by simply searching with two or more of any of the following: source:, -source:, and ~source:.
I discovered this bug when trying to use source:twimg -source:orig to find possible BVAS posts, being those that are directly uploaded from Twitter that don't include the "orig" extension necessary to get some of the best images.

Errors or other messages returned (if any).
No errors returned, except "No posts matched your search." if using ~source:.