"Raw" alphabet of alignment when there is sequence with one character

Scenario:

1. Open the attached file "small_with_one_char.fa" in UGENE.
2. Select "Join sequences into alignment and open in multiple alignment viewer" option in the "Sequence Reading Options" dialog, click "OK".
   Expected result: the alignment alphabet is "Standard amino acid" (the alignment is colored and the corresponding alphabet is specified on the "General" tab of the options panel).
   Current result: the alignment alphabet is "Raw".

It seems that the issue happens because an incorrect regular expression that parses an input sequence string. More exactly, it is incorrect when an input sequence has only one character.