Is it a bug?

If you enable re 'debug', then you'll get to see what's going on in detail. The compiled regexes differ in much the way you'd expect:

Final program:                               Final program:
   1: BOL (2)                                   1: BOL (2)
   2: OPEN1 (4)                                 2: OPEN1 (4)
   4:   PLUS (6)                                4:   PLUS (6)
   5:     REG_ANY (0)                           5:     REG_ANY (0)
   6: CLOSE1 (8)                                6: CLOSE1 (8)
   8: OPEN2 (10)                                8: OPEN2 (10)
  10:   PLUS (12)                              10:   PLUS (12)
  11:     REG_ANY (0)                          11:     REG_ANY (0)
  12: CLOSE2 (14)                              12: CLOSE2 (14)
  14: OPEN3 (16)                               14: OPEN3 (16)
  16:   PLUS (18)                              16:   CURLYX[2] {1,3276
+7} (24)
  17:     REG_ANY (0)                          18:     REG_ANY (19)
                                               19:     CURLY {0,1} (23
+)
                                               21:       EXACT <z> (0)
                                               23:   WHILEM[1/1] (0)
                                               24:   NOTHING (25)
  18: CLOSE3 (20)                              25: CLOSE3 (27)
  20: EOL (21)                                 27: EOL (28)
  21: EVAL (23)                                28: EVAL (30)
  23: OPFAIL (24)                              30: OPFAIL (31)
  24: END (0)                                  31: END (0)

[download]

Comparing the traces is harder.

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In reply to Re: Bug with finding all regexp matches by BrowserUk
in thread Bug with finding all regexp matches by Anonymous Monk

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