xdg-open doesn't wait for background processes, breaking terminal apps launched with Terminal=false

The merge of !55 (merged) has broken my workflow. I am using sway, so xdg-open will fallback to open_generic. When I open a terminal and type xdg-open file.txt, it now runs env vim file.txt & (the & was added in !55 (merged)), and exits. Terminal applications like vim or Helix don't like this and fail with:

Vim: Warning: Input is not from a terminal
~ $ Vim: Error reading input, exiting...

Or:

Error: Input/output error (os error 5)

I know that the merge request says "the current approach waits for the program to exit, which is not consistent with how various DE's launching scripts work." and that gio also doesn't wait, but this behavior is particularly bad in combination with #84 and is annoying some people.

I don't know a good solution to this since launching terminal apps in the current terminal seems impossible with gio.