Fix to allow any remote name to be used

src/errors.rs

@@ -1,3 +1,5 @@
+use std::path::PathBuf;
+
 error_chain! {
     foreign_links {
         Io(::std::io::Error) #[doc = "An error from the std::io module"];
@@ -75,5 +77,15 @@ error_chain! {
             description("Failed to parse a version for a dependency")
             display("The version `{}` for the dependency `{}` couldn't be parsed", version, dep)
         }
+        /// Missing registrary checkout in the cargo registrary
+        MissingRegistraryCheckout(path: PathBuf) {
+            description("Missing registrary checkout in the cargo registrary")
+            display("Looks like ({}) is empty", path.display())
+        }
+        /// Non Unicode git path
+        NonUnicodeGitPath {
+            // this is because git2 function takes &str insted of something like AsRef<Path>
+            description("Path to cargos registrary contains non unicode characters")
+        }
     }
 }

src/fetch.rs

@@ -123,8 +123,8 @@ pub fn update_registry_index(registry: &Url) -> Result<()> {
     output.reset()?;
     writeln!(output, " '{}' index", registry)?;
 
-    let refspec = "refs/heads/master:refs/remotes/origin/master";
-    fetch_with_cli(&repo, registry.as_str(), refspec)?;
+    let refspec = format!("refs/heads/{0}:refs/remotes/origin/{0}", get_checkout_name(registry_path)?);
+    fetch_with_cli(&repo, registry.as_str(), &refspec)?;
 
     Ok(())
 }
@@ -260,15 +260,33 @@ fn get_no_latest_version_from_json_when_all_are_yanked() {
     assert!(read_latest_version(&versions, false).is_err());
 }
 
+/// Gets the checkedout branch name of .cargo/registry/index/git.832008.xyz-*/.git/refs
+fn get_checkout_name(registry_path: impl AsRef<Path>) -> Result<String> {
+    let checkout_dir = registry_path.as_ref().join(".git").join("refs/remotes/origin/");
+    Ok(checkout_dir
+        .read_dir()?
+        .next() //Is there always only one branch? (expecting either master og HEAD)
+        .ok_or_else(|| ErrorKind::MissingRegistraryCheckout(checkout_dir))??
+        .file_name()
+        .into_string()
+        .map_err(|_| ErrorKind::NonUnicodeGitPath)?)
+}
+
 /// Fuzzy query crate from registry index
 fn fuzzy_query_registry_index(
     crate_name: impl Into<String>,
     registry_path: impl AsRef<Path>,
 ) -> Result<Vec<CrateVersion>> {
     let crate_name = crate_name.into();
-    let repo = git2::Repository::open(registry_path)?;
+    let remotes = PathBuf::from("refs/remotes/origin/");
+    let repo = git2::Repository::open(&registry_path)?;
     let tree = repo
-        .find_reference("refs/remotes/origin/master")?
+        .find_reference(
+            remotes
+                .join(get_checkout_name(&registry_path)?)
+                .to_str()
+                .ok_or_else(|| ErrorKind::NonUnicodeGitPath)?,
+        )?
         .peel_to_tree()?;
 
     let mut names = gen_fuzzy_crate_names(crate_name.clone())?;