Fix download-logs template

- Do not insert an extra slash into the download URL, this breaks on
  some storage providers.
- Do not try to uncompress *.xz files, libcurl cannot handle that
  compression, also these are mostly journal files that are compressed
  for a good reason.
- Mention the download directory again at the end, avoids needing to
  scroll through umpteen log messages in order to find out the name of
  the tmpdir generated at the start of the script.

Change-Id: I8eb674121a9808dfc8edfc14b8c3525a77b518ab

roles/local-log-download/templates/download-logs.sh.j2

@@ -65,8 +65,15 @@ EOF
 function save_file {
     local base_url="$1"
     local file="$2"
+    local xtra_args="--compressed"
 
-    curl -s --compressed --create-dirs -o "${file}" "${base_url}/${file}"
+   {#
+    # Do not uncompress .xz, libcurl cannot handle it
+   #}
+    if [[ "${file}" == *.xz ]]; then
+        xtra_args=""
+    fi
+    curl -s ${xtra_args} --create-dirs -o "${file}" "${base_url}${file}"
    {#
     # Using --compressed we will send an Accept-Encoding: gzip header
     # and the data will come to us across the network compressed.
@@ -114,4 +121,4 @@ done
 
 popd >/dev/null
 
-log "Download complete!"
+log "Download to ${DOWNLOAD_DIR} complete!"