main: If the default branch is not "master", set cgitrc defbranch

In order for CGit to know that the repository uses a default branch that
isn't "master", we need to set the `defbranch` setting in 'cgitrc'.

The mtime is read from either the "master" ref or the ref specified with
`defbranch`:
https://git.zx2c4.com/cgit/tree/ui-repolist.c?id=5258c297ba6fb604ae1415fbc19a3fe42457e49e#n56

1 files changed, 19 insertions, 0 deletions

diff --git a/src/main.rs b/src/main.rs
index a28eac2..0cf4328 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -259,6 +259,10 @@ where
             ))?;
     }
 
+    if repo.default_branch != "master" {
+        repo_cgitrc_set_defbranch(&clone_path, &repo.default_branch)?;
+    }
+
     update_mtime(&clone_path, &repo)?;
 
     Ok(())
@@ -284,6 +288,8 @@ fn update<P: AsRef<Path>>(
                 &repo_path,
                 &updated_repo.default_branch,
             )?;
+
+            repo_cgitrc_set_defbranch(&repo_path, &updated_repo.default_branch)?;
         }
     }
 
@@ -395,6 +401,19 @@ fn set_agefile_time<P: AsRef<Path>>(
     Ok(())
 }
 
+/// Set the default CGit branch in the repository's "cgitrc" file.
+fn repo_cgitrc_set_defbranch<P: AsRef<Path>>(
+    repo_path: P,
+    default_branch: &str,
+) -> anyhow::Result<()> {
+    repo_cgitrc_append(
+        &repo_path,
+        &format!("defbranch={}", default_branch),
+    )?;
+
+    Ok(())
+}
+
 /// Append `config` to the repo-local "cgitrc" file.
 fn repo_cgitrc_append<P: AsRef<Path>>(
     repo_path: P,