This issue was solved with changeset r32349.
Eric, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.
string.c (tr_trans): free heap ptr when the str is not embeded.
patched by Eric Wong. [Bug #4956] [ruby-core:37708]
Ya, I think that should be worded like "Don't report bugs here" or
something. Whenever I commit things that need to be backported, I file
a ticket there so yugui knows the revisions I want backported so that
she doesn't have to review every commit to trunk.