Arg.  One last bit of churn.

dkg found a bug in the new sanitize_string function that was causing
segfaults on messages with empty headers.  This is obviously an imprtant
thing to fix.

After chatting with some folks on #notmuch, we decided that the debian
build dependency on libgmime 2.4.24 is a bit too extreme, particularly
since it will actually prevent the package from being uploaded to
debian.  I therefore rolled-back the stricter build dependency.

A new version of release-candidate/0.6 is pushed.

jamie.

[0] git://finestructure.net/notmuch
    release-candidate/0.6
    aac1936bc9f878bd9ad2e097c5a686e146b73143