Fix const Option::unwrap_or()

Fixes #57

src/lib.rs

@@ -1,5 +1,4 @@
 #![feature(io_error_more)]
-#![feature(const_option_ext)]
 #![forbid(unsafe_code)]
 
 use std::path::Path;

src/provider/github.rs

@@ -9,8 +9,10 @@ use super::Project;
 use super::Provider;
 
 const ACCEPT_HEADER_JSON: &str = "application/vnd.github.v3+json";
-const GITHUB_API_BASEURL: &str =
-    option_env!("GITHUB_API_BASEURL").unwrap_or("https://api.github.com");
+const GITHUB_API_BASEURL: &str = match option_env!("GITHUB_API_BASEURL") {
+    Some(url) => url,
+    None => "https://api.github.com",
+};
 
 #[derive(Deserialize)]
 pub struct GithubProject {

src/provider/gitlab.rs

@@ -9,7 +9,10 @@ use super::Project;
 use super::Provider;
 
 const ACCEPT_HEADER_JSON: &str = "application/json";
-const GITLAB_API_BASEURL: &str = option_env!("GITLAB_API_BASEURL").unwrap_or("https://gitlab.com");
+const GITLAB_API_BASEURL: &str = match option_env!("GITLAB_API_BASEURL") {
+    Some(url) => url,
+    None => "https://gitlab.com",
+};
 
 #[derive(Deserialize)]
 #[serde(rename_all = "lowercase")]