Only include git-commit-hash in tarballs when available

… instead of writing an empty file.

Author: SimonSapin

src/bootstrap/dist.rs

@@ -364,9 +364,10 @@ impl Step for Rustc {
         cp("README.md");
         // tiny morsel of metadata is used by rust-packaging
         let version = build.rust_version();
-        let sha = build.rust_sha().unwrap_or("");
         t!(t!(File::create(overlay.join("version"))).write_all(version.as_bytes()));
-        t!(t!(File::create(overlay.join("git-commit-hash"))).write_all(sha.as_bytes()));
+        if let Some(sha) = build.rust_sha() {
+            t!(t!(File::create(overlay.join("git-commit-hash"))).write_all(sha.as_bytes()));
+        }
 
         // On MinGW we've got a few runtime DLL dependencies that we need to
         // include. The first argument to this script is where to put these DLLs
@@ -846,8 +847,9 @@ impl Step for PlainSourceTarball {
 
         // Create the version file
         write_file(&plain_dst_src.join("version"), build.rust_version().as_bytes());
-        let sha = build.rust_sha().unwrap_or("");
-        write_file(&plain_dst_src.join("git-commit-hash"), sha.as_bytes());
+        if let Some(sha) = build.rust_sha() {
+            write_file(&plain_dst_src.join("git-commit-hash"), sha.as_bytes());
+        }
 
         // If we're building from git sources, we need to vendor a complete distribution.
         if build.rust_info.is_git() {
@@ -1160,9 +1162,10 @@ impl Step for Extended {
         install(&build.src.join("LICENSE-APACHE"), &overlay, 0o644);
         install(&build.src.join("LICENSE-MIT"), &overlay, 0o644);
         let version = build.rust_version();
-        let sha = build.rust_sha().unwrap_or("");
         t!(t!(File::create(overlay.join("version"))).write_all(version.as_bytes()));
-        t!(t!(File::create(overlay.join("git-commit-hash"))).write_all(sha.as_bytes()));
+        if let Some(sha) = build.rust_sha() {
+            t!(t!(File::create(overlay.join("git-commit-hash"))).write_all(sha.as_bytes()));
+        }
         install(&etc.join("README.md"), &overlay, 0o644);
 
         // When rust-std package split from rustc, we needed to ensure that during