Merge branch 'collectd-5.7' into collectd-5.8

diff --cc src/collectd.conf.in
Simple merge

diff --cc src/collectd.conf.pod
Simple merge

diff --cc src/daemon/meta_data.c
index ce3e10206de8a065198d9f53f877d8a0e0f26e85,7684690437575b3ec9b720a1055af15f232b09cc..4d59b7126523cef10357b0b71c29e55c177eaab5
--- 1/src/daemon/meta_data.c
--- 2/src/daemon/meta_data.c
+++ b/src/daemon/meta_data.c
@@@ -737,9 -737,8 +737,8 @@@ int meta_data_as_string(meta_data_t *md
  
    temp = md_strdup(actual);
    if (temp == NULL) {
-     pthread_mutex_unlock(&md->lock);
      ERROR("meta_data_as_string: md_strdup failed for key `%s'.", key);
 -    return (-ENOMEM);
 +    return -ENOMEM;
    }
  
    *value = temp;