Autocomplete does not replace query-string on selection

[mervn]

When auto-completing an account name via ^X^O, the query-string (i.e Eq:Ope) is not replaced by the selected string (i.e Equity:Opening-Balances). Here is the expected behavior:

1. 2000-01-01 close Eq:Ope
2. While in input mode, with your cursor at the end-of-line, press Control-X then Control-O
3. Select "Equity:Opening-Balances"
4. 2000-01-01 close Equity:Opening-Balances

Here is the unexpected behavior that occurs:

1. 2000-01-01 close Eq:Ope
2. While in input mode, with your cursor at the end-of-line, press Control-X then Control-O
3. Select "Equity:Opening-Balances"
4. 2000-01-01 close Eq:OpeEquity:Opening-Balances

I use the term (un)expected, but I'm actually not sure what the intended behavior is here. If what I call "unexpected" is actually expected, then I am requesting for it to be changed - as it is intuitive for a replacement function to replace the original string; If not, then this a bug report.