From ce40ab87c8102b457118bb5c0f868593c4fb8c85 Mon Sep 17 00:00:00 2001
From: Dale Wijnand <dale.wijnand@gmail.com>
Date: Thu, 18 Oct 2018 06:44:12 +0100
Subject: [PATCH] Preserve multiline top comments

---
 src/cargo/ops/lockfile.rs | 10 ++++------
 tests/testsuite/update.rs |  1 +
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/cargo/ops/lockfile.rs b/src/cargo/ops/lockfile.rs
index 4deb7d116..103876264 100644
--- a/src/cargo/ops/lockfile.rs
+++ b/src/cargo/ops/lockfile.rs
@@ -43,12 +43,10 @@ pub fn write_pkg_lockfile(ws: &Workspace, resolve: &Resolve) -> CargoResult<()>
 
     let mut out = String::new();
 
-    if let Ok(ref orig) = orig {
-        if let Some(first_line) = orig.lines().into_iter().next() {
-            if first_line.starts_with("#") {
-                out.push_str(first_line);
-                out.push_str("\n");
-            }
+    if let Ok(orig) = &orig {
+        for line in orig.lines().take_while(|line| line.starts_with("#")) {
+            out.push_str(line);
+            out.push_str("\n");
         }
     }
 
diff --git a/tests/testsuite/update.rs b/tests/testsuite/update.rs
index 0b120daa9..be527b288 100644
--- a/tests/testsuite/update.rs
+++ b/tests/testsuite/update.rs
@@ -383,6 +383,7 @@ fn preserve_top_comment() {
 
     let mut lockfile = p.read_file("Cargo.lock");
     lockfile.insert_str(0, "# @generated\n");
+    lockfile.insert_str(0, "# some other comment\n");
     println!("saving Cargo.lock contents:\n{}", lockfile);
 
     p.change_file("Cargo.lock", &lockfile);