adds Clone to OwnedMeasurement

src/influx.rs

@@ -243,6 +243,7 @@ pub enum OwnedValue {
     Boolean(bool)
 }
 
+#[derive(Clone)]
 pub struct OwnedMeasurement {
     pub key: &'static str,
     pub timestamp: Option<i64>,
@@ -281,6 +282,11 @@ impl OwnedMeasurement {
         self.timestamp = Some(timestamp);
         self
     }
+
+    pub fn set_tag(mut self, key: &'static str, value: &'static str) -> Self {
+        *self.tags.entry(key).or_insert(value) = value;
+        self
+    }
 }
 
 pub fn dur_nanos(d: ::std::time::Duration) -> i64 {