From: Debian Rust Maintainers <pkg-rust-maintainers@alioth-lists.debian.net>
Date: Thu, 14 Jul 2022 13:17:38 +0200
Subject: d-bootstrap-read-beta-version-from-file

===================================================================
---
 src/bootstrap/lib.rs | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 68d387b..ddc92ba 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -1267,15 +1267,13 @@ impl Build {
             return s;
         }
 
-        // Figure out how many merge commits happened since we branched off master.
-        // That's our beta number!
-        // (Note that we use a `..` range, not the `...` symmetric difference.)
+        // Debian: read beta number from "version" file, this is only available
+        // in the rustc upstream tarballs and not their git
         let count = output(
-            Command::new("git")
-                .arg("rev-list")
-                .arg("--count")
-                .arg("--merges")
-                .arg("refs/remotes/origin/master..HEAD")
+            Command::new("sed")
+                .arg("-re")
+                .arg(r"s/[0-9]+.[0-9]+.[0-9]+-beta.([0-9]+) \(.*\)/\1/g")
+                .arg("version")
                 .current_dir(&self.src),
         );
         let n = count.trim().parse().unwrap();