Fix bzgrep so it doesn't always return a 0 exit code

Bzgrep used to always returns 0 as an exit code when grepping multiple
archives; this fixes it.

Patch from Kristýna Streitová <kstreitova@suse.com>

bzgrep

@@ -65,8 +65,20 @@ for i do
   else
     j=$(echo "$i" | sed 's/\\/&&/g;s/|/\\&/g;s/&/\\&/g')
     j=`printf "%s" "$j" | tr '\n' ' '`
-    bzip2 -cdfq "$i" | $grep $opt "$pat" | sed "s|^|${j}:|"
-    r=$?
+    # A trick adapted from
+    # https://groups.google.com/forum/#!original/comp.unix.shell/x1345iu10eg/Nn1n-1r1uU0J
+    # that has the same effect as the following bash code:
+    # bzip2 -cdfq "$i" | $grep $opt "$pat" | sed "s|^|${j}:|"
+    # r=${PIPESTATUS[1]}
+    exec 3>&1
+    eval `
+      exec 4>&1 >&3 3>&-
+      {
+        bzip2 -cdfq "$i" 4>&-
+      } | {
+        $grep $opt "$pat" 4>&-; echo "r=$?;" >&4
+      } | sed "s|^|${j}:|"
+    `
   fi
   test "$r" -ne 0 && res="$r"
 done