Improve ExtractsPath logic related to atom format

* Don't set request format to atom if '.atom' suffix was not provided
* Don't try '.atom' detection logic on request that uses extended_sha1
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

lib/extracts_path.rb

@@ -113,18 +113,19 @@ module ExtractsPath
     @id = get_id
     @ref, @path = extract_ref(@id)
     @repo = @project.repository
-    if @options[:extended_sha1].blank?
-      @commit = @repo.commit(@ref)
-    else
+
+    if @options[:extended_sha1].present?
       @commit = @repo.commit(@options[:extended_sha1])
-    end
+    else
+      @commit = @repo.commit(@ref)
 
-    if @path.empty? && !@commit
+      if @path.empty? && !@commit && @id.ends_with?('.atom')
         @id = @ref = extract_ref_without_atom(@id)
         @commit = @repo.commit(@ref)
 
         request.format = :atom if @commit
       end
+    end
 
     raise InvalidPathError unless @commit