[Dovecot] Broken sorting(?)

Somewhere between revision f5554ae61732 (12 days ago) and the release
of 1.2a4 (f53952ac4285; 9 days ago) sorting appears to have broken.
With the older revision, I see the following (using Maildir):

a sort (ARRIVAL) US-ASCII ALL

• SORT 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
  26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
  49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71
  72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94
  95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113
  114 115 116 117 118 119 120 121 122 123 124 2 1

With the newest code, I see this:

a sort (ARRIVAL) US-ASCII ALL

• SORT 124 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
  25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
  48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70
  71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93
  94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112
  113 114 115 116 117 118 119 120 121 122 123 124 2 1

Obviously, that duplicate sequence number (124) is not a good thing
(shouldn't the sequence numbers be in order for an arrival search
anyway?). Deleting any message in the mailbox always makes the last
sequence number appear at the beginning.

I can verify that another IMAP server on the same machine views the
mailbox just fine: a sort (arrival) US-ASCII ALL

• SORT 124 123 122 121 120 119 118 117 116 115 114 113 112 111 110 109
  108 107 106 105 104 103 102 101 100 99 98 97 96 95 94 93 92 91 90 89
  88 87 86 85 84 83 82 81 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66
  65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43
  42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20
  19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

michael