Comment 12 for bug 1445239

I've seen this a few times. It appears to be an issue with recovering partially downloaded files, and my workaround was to rm /var/lib/apt/lists/partial/*

Looking through some notes from a few weeks ago, the backtrace was:

(gdb) backtrace
#0 0x00003fffb5b5d6ec in SHA1Transform (state=state@entry=0x3fffecb9b5e0,
    buffer=buffer@entry=0x3fffecb97043 "f\350'\315\060\372C343\345\030\301b\212'\371\376\271\202\237uiF\247\325\361\245\017o\277\344\031\245\275\370\361\256=C\033\277Y\b\242\021\257I\233\245\321FU\220\216{(\327J\nlB\021\364\360\373\311\066$\304\303\001\031\\\352Þ‚\024\271\\\321\f\023\255\342tK?b\f\361\306j\037\325\323\nH\036\061\026J\313A0d\306Bo\006\031\246q8\361W\247b@\243\373\322\316a\240y\226tC\213\271#'\"\301N\030pDb\203D\234gEz\237\031\341\062\020ÄŠÙªK\276\232\201!\332T\227\\\026\242\034\270\031ÛŒ\273\272\036\033\006\257q\255u\350\243*\332\373\256\256\205m1 \213\266*\\eN\033\272a"...)
    at /build/buildd/apt-1.0.9.7ubuntu4/apt-pkg/contrib/sha1.cc:108
#1 0x00003fffb5b5ec9c in SHA1Summation::Add (this=0x3fffecb9b598,
    data=0x3fffecb87c10 "n\202\341\067\231\267g\251N\316\324[0\361\070\230`sxtй\300b\200Y\347\252V\323 \310ƃ\273I'\236", len=65536)
    at /build/buildd/apt-1.0.9.7ubuntu4/apt-pkg/contrib/sha1.cc:262
#2 0x00003fffb5c7a6e0 in Add (Size=65536,
    Data=0x3fffecb87c10 "n\202\341\067\231\267g\251N\316\324[0\361\070\230`sxtй\300b\200Y\347\252V\323 \310ƃ\273I'\236", this=0x3fffecb9b530)
    at ../build/include/apt-pkg/hashes.h:167
#3 CircleBuf::Write (this=0x3fffecb83b90, Fd=4)
    at /build/buildd/apt-1.0.9.7ubuntu4/methods/http.cc:222
#4 0x00003fffb5c7b518 in HttpServerState::Go (this=0x3fffecb83960, File=
    0x3fffecb81980, ToFile=true)
    at /build/buildd/apt-1.0.9.7ubuntu4/methods/http.cc:652

We were stuck in the circular buffer code, the input and output pointers got out of whack such that we would write the same buffer continually.