alt should be some plain text.

Wikitext:

<gallery>
File:Wiki.png|cap'''t'''ion|alt=x'''y'''z
</gallery>

Actual:

<ul class="gallery">
<li class="gallerybox" style="width: 155px">
<div style="width: 155px">
<div class="thumb" style="width: 150px;">
<div style="margin:15px auto;"><a href="/wiki/File:Wiki.png" class="image"><img alt="xyz" src="//upload.wikimedia.org/wikipedia/en/thumb/b/bc/Wiki.png/104px-Wiki.png" width="104" height="120" /></a></div>
</div>
<div class="gallerytext">
<p>cap<b>t</b>ion</p>
</div>
</div>
</li>
</ul>

Expected:

<ul class="gallery">
<li class="gallerybox" style="width: 155px">
<div style="width: 155px">
<div class="thumb" style="width: 150px;">
<div style="margin:15px auto;"><a href="/wiki/File:Wiki.png" class="image"><img alt="x'''y'''z" src="//upload.wikimedia.org/wikipedia/en/thumb/b/bc/Wiki.png/104px-Wiki.png" width="104" height="120" /></a></div>
</div>
<div class="gallerytext">
<p>cap<b>t</b>ion</p>
</div>
</div>
</li>
</ul>

Version: 1.22.0
Severity: normal