Versions
WorldEdit version: Bukkit-Official 7.2.0-SNahshot+4947-404feef
Platform version: git-Paper-221 (MC 1.14.4)

Describe the bug
When tab completing patterns with percentages, whenever you type the percentage and put the percentage sign, right after it, a list of completions with the percentage sign should pop up, but none do. However, when you press a letter right after the percentage sign, you do get a list, but each item in that list does not have the percentage you put in front and when you tab complete to it, it removes the most recently typed percentage. (see the gif)

To Reproduce

1. Start typing a pattern with a percentage
2. Right after the percent sign is placed try to tab-complete (there should be nothing)
3. Press any letter which a material begins with and try to tab-complete
4. Your tab completion works, but without the percentage you gave it

Expected behavior
When you tab-complete a percentage, what ideally would happen is right after the percentage sign, you get a whole list of all the materials you can use appended to the percentage string.

Screenshots
https://cdn.discordapp.com/attachments/421260739970334720/700414711832903760/worldedit-tab-completion.gif

Additional context
The percentage going away only affects the most recently typed percentage. Eg: 20%stone,30%gravel,10%bedrock (if you tab completed the bedrock part of the pattern, the 10% goes away)