Changing the order of shown columns in a custom issue query destroys the column selection
Steps to reproduce:
1. log in Redmine
2. open "My page", then "Issues assigned to me" (or any other, I guess)
3. customize the query by adding a column at the end of the list (e.g. "Done %")
4. save the query ("Test query")
Now we have a new custom query.
5. edit that query
6. pick the last column (the one just added) from the "Selected columns" list, move it up one position
7. save the query
Only one column is left.