MDL-40633 filter_urltolink breaking some image links.

This was a regression caused by MDL-22390. HTML like
<img src="http://www.example.com/logo.gif" />
was being broken.
Automatically generated installer lang files
Merge branch 'install_23_STABLE' of git://git.moodle.cz/moodle-install into MOODLE_23_STABLE
weekly release 2.3.8+
Automatically generated installer lang files
weekly release 2.3.8+
Merge branch 'MOODLE_23_STABLE' into install_23_STABLE
Automatically generated installer lang files
MDL-40615 Repository: Updated Amazon S3 library

Fixed insecure use of CURLOPT_SSL_VERIFYHOST
Merge branch 'install_23_STABLE' of git://git.moodle.org/moodle-install into MOODLE_23_STABLE
weekly release 2.3.8+
Automatically generated installer lang files
MDL-40889 prevent 304 when minimising JS
Automatically generated installer lang files
Merge branch 'install_23_STABLE' of git://git.moodle.org/moodle-install into MOODLE_23_STABLE
weekly release 2.3.8+
Automatically generated installer lang files
weekly release 2.3.8+
Automatically generated installer lang files
Automatically generated installer lang files