APTのSEGVが瞬時に直された 

=== modified file 'apt-pkg/acquire-item.cc'
--- apt-pkg/acquire-item.cc     2011-03-14 15:27:24 +0000
+++ apt-pkg/acquire-item.cc     2011-04-02 19:00:45 +0000
@@ -841,7 +841,7 @@
    if (ShortDesc().find("Translation") != 0)
       msg += "\nFail-Ignore: true";
    struct stat Buf;
-   if (stat(Final.c_str(),&Buf) != 0)
+   if (stat(Final.c_str(),&Buf) == 0)
       msg += "\nLast-Modified: " + TimeRFC1123(Buf.st_mtime);

    return msg;

まさかIA-64関係なく，全アーキで腐ってたとは思わなかった．Debian testing AMD64のこのPCでは何事もなく動いてるんですが．

// AcqIndex::Custom600Headers - Insert custom request headers		/*{{{*/
// ---------------------------------------------------------------------
/* The only header we use is the last-modified header. */
string pkgAcqIndex::Custom600Headers()
{
   string Final = _config->FindDir("Dir::State::lists");
   Final += URItoFileName(RealURI);
   if (_config->FindB("Acquire::GzipIndexes",false))
      Final += ".gz";
   
   string msg = "\nIndex-File: true";
   // FIXME: this really should use "IndexTarget::IsOptional()" but that
   //        seems to be difficult without breaking ABI
   if (ShortDesc().find("Translation") != 0)
      msg += "\nFail-Ignore: true";
   struct stat Buf;
   if (stat(Final.c_str(),&Buf) == 0)
      msg += "\nLast-Modified: " + TimeRFC1123(Buf.st_mtime);
   return msg;
}

 // TimeRFC1123 - Convert a time_t into RFC1123 format.  .       .       /*{{{*/
 // ---------------------------------------------------------------------
 /* This converts a time_t into a string time representation that is
    year 2000 complient and timezone neutral */
 string TimeRFC1123(time_t Date)
 {
    struct tm Conv = *gmtime(&Date);
    char Buf[300];
 
    const char *Day[] = {"Sun","Mon","Tue","Wed","Thu","Fri","Sat"};
    const char *Month[] = {"Jan","Feb","Mar","Apr","May","Jun","Jul",
                           "Aug","Sep","Oct","Nov","Dec"};
 
    sprintf(Buf,"%s, %02i %s %i %02i:%02i:%02i GMT",Day[Conv.tm_wday],
            Conv.tm_mday,Month[Conv.tm_mon],Conv.tm_year+1900,Conv.tm_hour,
            Conv.tm_min,Conv.tm_sec);
    return Buf;
 }

うーん， struct stat をstack上に取った後，中身を stat(2) が更新しないままで（stat(2) の成功を調べる条件が逆だった）， time_t st_mtime のゴミを参照してた訳だが，だからってSEGVるもんだろうか？
ともあれ，これでしばらく待てばtestingに降りてくるから，普通に aptitude update できるようになる．