[Dovecot] rc15 sort bug

[Cor Bosman]

Hi, ive come across what looks like a bug in how dovecot sorts the
mail when sorting on subject. We noticed this on our current beta8
version, and I can also reproduce it in rc15. 

One of our customers has hundreds of emails with subjects like this:

Subject: 20060823 Kanglaonline-NSCN(IM) cadres violating Tml truce: NSCN(K) 
Subject: 20060824 LSE - Shell jv denies 3.2 bln usd fraud claims by Nigerian parliament
Subject: =?iso-8859-1?Q?20060824_Ibinda_-_Onze_militares_angolanos_mortos_em_comba?=
Subject: =?iso-8859-1?Q?20060824_Gingaocultural=2C_VoA_-_Deputados_constatam_clima?=

Some of the Subject lines are encoded, some arent. All the encoded Subject
lines end up being sorted wrong. 

Here is a UID SORT output:

* SORT 3 4 5 10 20 26 27 28 29 30 33 35 36 37 39 43 44 46 47 58 59 60 83 85 87 8
8 89 90 93 112 113 115 116 118 124 126 127 130 131 132 134 135 137 139 140 141 1
79 205 206 208 209 210 211 212 215 217 226 237 238 240 241 250 282 283 285 291 2
92 293 314 315 316 317 318 319 320 321 328 329 330 337 355 377 378 379 380 381 3
82 383 384 385 407 411 413 423 427 398 409 367 374 376 371 348 372 353 369 400 3
66 352 396 50 370 354 402 347 404 412 415 356 419 408 414 420 388 243 251 21 386
 31 1 2 7 6 9 8 349 13 11 12 32 15 34 14 16 22 23 18 17 25 24 19 45 38 48 397 40
3 49 41 40 42 421 56 82 54 53 51 55 52 57 86 63 64 61 62 65 67 71 66 77 76 72 74
 75 68 70 84 69 73 80 81 78 79 91 92 128 133 94 97 98 95 96 242 100 102 99 101 1
03 249 114 105 104 247 108 106 107 109 111 375 110 117 387 322 129 125 136 122 1
21 123 144 143 120 233 119 138 142 166 214 149 156 153 155 152 158 159 165 162 1
51 157 154 148 150 160 145 146 147 161 410 418 417 163 164 172 168 173 171 170 1
69 167 178 174 175 176 177 180 184 181 182 186 183 185 213 389 230 232 207 231 2
29 246 216 234 248 225 390 189 275 277 187 340 204 200 197 195 194 192 193 191 1
99 198 196 416 188 190 391 350 201 218 202 245 203 361 228 279 239 220 224 221 2
23 222 235 244 219 280 236 281 278 252 254 304 351 256 257 253 255 274 276 273 2
64 265 263 261 262 258 272 260 259 294 357 227 290 269 286 358 266 270 271 268 2
87 267 288 284 289 359 310 309 307 303 305 306 373 295 300 297 298 296 299 311 3
12 302 308 301 313 332 325 326 324 323 333 346 327 331 362 334 339 335 336 360 3
41 344 338 345 342 343 401 365 392 363 368 399 394 405 395 406 422 424 425 426 4
29 428 393

For instance, UID 112 is an encoded subject and should appear after UID 111
later on in the output. 

Bug or feature?

Regards,

Cor Bosman
XS4ALL