Issues with shortcut links converted to reference links

[danpla]

Consider the following test.md file:

Text with [link1] and [link2].

[LINK1]: example.com
[link2]: example.com

md2po test.md gives the following msgid:

msgid "Text with [link1][LINK1] and [link2][LINK1]."

As you see, there are two strange things:

• Although link labels are case-insensitive, a shortcut link is unnecessarily converted to a reference link if the label has different letter case.
• [link2] surprisingly turned into [link2][LINK1], apparently because both link references have the same URL.

md2po 1.1.3