Hi swu,
I would not say this is a bug... This consequence of newly added auto complete feature...
And only happens if
match case is disabled (this is by design) so search works well independently from case.
I do not see the way, how I can make this better, without disabling auto-complete feature.
The suggest feature works in the way, that if matching string is found, it replaces typed string and selects the rest, so if you continue typing - you delete ending. If not, and you press tab, the value is filled and you can search.
In the example case, when you type "u", HE replaces it by "Use" from history, it does not know that you will not accept it. So because only ending "se" is selected, when you continue typing, replaced "U" is left. OK, what will happen, if HE will retain typed part "u". In you example, everything will be fine: you type "pper" (sorry I mix the example, but does not matter) and get "upper".
But what if there was already "UPPER" in the history. That mean that if typed "u" retain, and you would like to get "UPPER" you will get "uPPER". Also not nice and somebody will complain.
I can place more logic there and check that new word is not complete upper case and only capitalize and retain prefix only in this case, but this will be also not 100% solution.
If you have some stable algorithm how to solve this - welcome

But nevertheless because this is not a bug, will be only in 1.50.
BR, Alex.