anchor.diff:                  NAME=\$(basename ${s} .bz2)
                   bzip2 -d <${s} > \$PWD/\$(basename ${s} .bz2)/\${NAME#*-}
                   cd \$(basename ${s} .bz2)
  +        " else if (archiveType s) == "plain-gz" then "
  +                mkdir \$PWD/\$(basename ${s} .gz)
  +                NAME=\$(basename ${s} .gz)
  +                gzip -d <${s} > \$PWD/\$(basename ${s} .gz)/\${NAME#*-}
  +                cd \$(basename ${s} .gz)
           " else (abort "unknown archive type : ${s}"))+
                   # goSrcDir is typically something like "cd mysubdir" .. but can be anything else 
                   (if args ? goSrcDir then args.goSrcDir else "")
  
positive.code:                 else if (hasSuffixHack ".tar.gz" s) || (hasSuffixHack ".tgz" s) then "tgz" 
                  else if (hasSuffixHack ".tar.bz2" s) || (hasSuffixHack ".tbz2" s) || 
  			(hasSuffixHack ".tbz" s) then "tbz2"
                  else if (hasSuffixHack ".tar.lzma" s) then "tar.lzma"
                  else if (hasSuffixHack ".zip" s) || (hasSuffixHack ".ZIP" s) then "zip"
                  else if (hasSuffixHack "-cvs-export" s) then "cvs-dir"
  
negative.code:         " else if (archiveType s) == "tbz2" then "
                  tar xvjf '${s}'
                  cd \"\$(tar tjf '${s}' | head -1 | sed -e 's@/.*@@' )\"
          " else if (archiveType s) == "tZ" then "
                  uncompress < '${s}' | tar x
                  cd \"\$(uncompress < '${s}' | tar t | head -1 | sed -e 's@/.*@@' )\"
          " else if (archiveType s) == "tar.lzma" then "
                  unlzma -d -c <'${s}' | tar xv
                  cd \"\$(unlzma -d -c <'${s}' | tar t | head -1 | sed -e 's@/.*@@' )\"
  