That's quite handy, and thanks for posting it, but sadly it does not explain why the marked branch sets the value of $1 to 'g' even though it "failed..." to match: 
Matching REx "(?:(.)b|.)+" against "ebfg"
   0 <> <ebfg>               |  1:CURLYX[0] {1,32767}(15)
   0 <> <ebfg>               | 14:  WHILEM[1/1](0)
                                    whilem: matched 0 out of 1..32767
   0 <> <ebfg>               |  3:    BRANCH(11)
   0 <> <ebfg>               |  4:      OPEN1(6)
   0 <> <ebfg>               |  6:      REG_ANY(7)
   1 <e> <bfg>               |  7:      CLOSE1(9)
   1 <e> <bfg>               |  9:      EXACTF <b>(14)
   2 <eb> <fg>               | 14:      WHILEM[1/1](0)
                                        whilem: matched 1 out of 1..32
+767
   2 <eb> <fg>               |  3:        BRANCH(11)
   2 <eb> <fg>               |  4:          OPEN1(6)
   2 <eb> <fg>               |  6:          REG_ANY(7)
   3 <ebf> <g>               |  7:          CLOSE1(9)
   3 <ebf> <g>               |  9:          EXACTF <b>(14)
                                            failed...
   2 <eb> <fg>               | 11:        BRANCH(13)
   2 <eb> <fg>               | 12:          REG_ANY(14)
   3 <ebf> <g>               | 14:          WHILEM[1/1](0)
                                            whilem: matched 2 out of 1
+..32767

[download]
   3 <ebf> <g>               |  3:            BRANCH(11)
   3 <ebf> <g>               |  4:              OPEN1(6)
   3 <ebf> <g>               |  6:              REG_ANY(7)
   4 <ebfg> <>               |  7:              CLOSE1(9)
   4 <ebfg> <>               |  9:              EXACTF <b>(14)
                                                failed...
   3 <ebf> <g>               | 11:            BRANCH(13)

[download]
   3 <ebf> <g>               | 12:              REG_ANY(14)
   4 <ebfg> <>               | 14:              WHILEM[1/1](0)
                                                whilem: matched 3 out 
+of 1..32767
   4 <ebfg> <>               |  3:                BRANCH(11)
   4 <ebfg> <>               |  4:                  OPEN1(6)
   4 <ebfg> <>               |  6:                  REG_ANY(7)
                                                    failed...
   4 <ebfg> <>               | 11:                BRANCH(13)
   4 <ebfg> <>               | 12:                  REG_ANY(14)
                                                    failed...
                                                  BRANCH failed...
                                                whilem: failed, trying
+ continuat
ion...
   4 <ebfg> <>               | 15:                NOTHING(16)
   4 <ebfg> <>               | 16:                END(0)
Match successful!
Test:             1='g', 2=''
Freeing REx: "(?:(.)b|.)+"

[download]

In reply to Re^2: Leaking Regex Captures by SuicideJunkie
in thread Leaking Regex Captures by SuicideJunkie

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