[BUG] Trailing commas in meta keywords when no tags or no keywords in metadata

[vokimon]

Mandatory Step

• I am using latest production release of Elegant

Recommended Step

• I have attached link to my blog source code repository, so that developers can try to reproduce the issue at the end
• I can't my source code but I have linked my pelican configuration files to help developers reproduce the issue

Description

Trailing commas appear in the content of the meta-keywords tag, whenever no tags or no keywords are set.

If you define *no keywords then a trailing comma will appear at the end.

<meta name="keywords" content="mytag1, mytag2, mycategory, " />

Likewise when metadata has no tags, a trailing comma appear at the end of the

<meta name="keywords" content=", mycategory, kwd1, kwd2" />

When both, keywords and tags, are missing, trailing commas appear at both sides:

<meta name="keywords" content=", mycategory, " />

While the expected outcome would be:

<meta name="keywords" content="mycategory" />

To reproduce it create a page with category but no tags or no keywords and generate the website. Then look at the generated meta-keyword tag.

The problem is that when there is no tags or no keywords, instead of a comma separated string 'tag' or 'tag1, tag2', an empty string '' is joined. The solution could be generating lists of keywords, tags, and the category, adding them as a single list and then applying the join.