When calling `:gopls definition`, the gopls LSP server returns the location of
the selected definition. Then, `gopls.kak` tries to parse this output to
feed the `:edit` command and open the file in Kakoune. To do this, it
uses `sed` to transform `<path>.go:<line>:<colstart>-<colend>` to `<path>.go
<line> <colstart>`. However, if the `<path>` contains a dash character,
the `sed` will fail and strip everything after this first dash, removing
the line and columns information.
Closes#4776