Stack overflow on commit

[Serg Masiutin]

Hi!

    Due to recursive nature of RCS_putdtree stack overflow occures on commit if 
file reaches some number of revisions (in my case 8152 under QNX/Neutrino). 
    I have rewritten it so to be linear (recursive only when file branches 
occur) and can send changed code for review. 
    But in any case think this rare bug must be fixed.

PS:
    I'm new to GNU development :-)

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Best regards,
    Serg Masyutin