Fixes issue where a non-link is falsely identified as a link and given the link text of a later link.
More info in thread: https://meta.discourse.org/t/http-gets-parsed-incorrectly-in-posts/24866
m flags together caused the above case. How this regex works, there isn’t any reason to use
g as the regex should match at the start of the given text being tested, and for
m that is for matching across lines, and links are not valid with multiple lines.