Use new Match::or to simplify return

ignore/src/dir.rs

@@ -360,19 +360,8 @@ impl Ignore {
         }
         let m_global = self.0.git_global_matcher.matched(&path, is_dir)
                            .map(IgnoreMatch::gitignore);
-        if !m_ignore.is_none() {
-            m_ignore
-        } else if !m_gi.is_none() {
-            m_gi
-        } else if !m_gi_exclude.is_none() {
-            m_gi_exclude
-        } else if !m_global.is_none() {
-            m_global
-        } else if !m_explicit.is_none() {
-            m_explicit
-        } else {
-            Match::None
-        }
+
+        m_ignore.or(m_gi).or(m_gi_exclude).or(m_global).or(m_explicit)
     }
 
     /// Returns an iterator over parent ignore matchers, including this one.

ignore/src/lib.rs

@@ -297,4 +297,13 @@ impl<T> Match<T> {
             Match::Whitelist(t) => Match::Whitelist(f(t)),
         }
     }
+
+    /// Return the match if it is not none. Otherwise, return other.
+    pub fn or(self, other: Self) -> Self {
+        if self.is_none() {
+            other
+        } else {
+            self
+        }
+    }
 }