build: record the actual build environment in .buildinfo

The binary build exported DEB_BUILD_OPTIONS='parallel=<context nproc>
nocheck' (or the -j override) but the generated .buildinfo recomputed
the environment from host state: host core count, no nocheck, and
vendor profiles that ignored DEB_BUILD_PROFILES (a cross build recorded
no 'cross' profile). generate_binary_metadata now records the exact env
map that was exported to the build steps, and the recorded profiles
come from the exported DEB_BUILD_PROFILES when set.

Also unifies vendor parsing on one helper (the context-side copy lacked
the Origin: fallback of the source-build path).

src/deb/local.rs

@@ -5,7 +5,7 @@ use crate::deb::find_dsc_file;
 use crate::ui::deb::{DebUi, Phase};
 use crate::ui::logfmt::QuiltClassifier;
 use log::warn;
-use std::collections::HashMap;
+use std::collections::{BTreeMap, HashMap};
 use std::error::Error;
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
@@ -420,10 +420,6 @@ fn generate_upload_metadata(
     env: &HashMap<String, String>,
     ctx: &Arc<Context>,
 ) -> Result<(PathBuf, PathBuf), Box<dyn Error>> {
-    let changelog_path = Path::new(package_dir).join("debian/changelog");
-    let changelog_content = ctx.read_file(&changelog_path)?;
-    let entry = crate::debian::parse_changelog_entry_from_str(&changelog_content)?;
-
     // Build architecture: the machine inside the build context.
     let build_arch = ctx
         .command("dpkg")
@@ -440,34 +436,37 @@ fn generate_upload_metadata(
         build_arch.clone()
     };
 
-    // Vendor resolution inside the context (falls back to the host view).
+    // Vendor resolution inside the context (falls back to the host view);
+    // shared `Vendor:`/`Origin:` parsing with the source-build path.
     let vendor = ctx
         .read_file(Path::new("/etc/dpkg/origins/default"))
         .ok()
-        .and_then(|content| {
-            for line in content.lines() {
-                if let Some(v) = line.strip_prefix("Vendor:") {
-                    let v = v.trim();
-                    if !v.is_empty() {
-                        return Some(v.to_string());
-                    }
-                }
-            }
-            None
-        })
+        .and_then(|content| crate::build::env::vendor_from_origins_content(&content))
         .unwrap_or_else(crate::build::env::current_vendor);
 
-    let profiles = crate::build::env::resolve_build_profiles(&[], &vendor);
-    let source_date_epoch = env
-        .get("SOURCE_DATE_EPOCH")
-        .and_then(|v| v.parse::<i64>().ok())
-        .unwrap_or(entry.timestamp);
+    // The recorded profiles must describe what the build actually ran with:
+    // the DEB_BUILD_PROFILES exported to the build steps ('cross' for cross
+    // builds), else the vendor defaults.
+    let profiles = match env.get("DEB_BUILD_PROFILES") {
+        Some(value) => value
+            .split(',')
+            .map(|p| p.trim().to_string())
+            .filter(|p| !p.is_empty())
+            .collect(),
+        None => crate::build::env::resolve_build_profiles(&[], &vendor),
+    };
+
+    // Record exactly the environment exported to the build steps
+    // (DEB_BUILD_OPTIONS with the real parallel count and 'nocheck', LANG=C,
+    // SOURCE_DATE_EPOCH, cross DEB_* variables, ...), not values recomputed
+    // from host state; buildinfo_environment filters out non-dpkg variables.
+    let exported_env: BTreeMap<String, String> =
+        env.iter().map(|(k, v)| (k.clone(), v.clone())).collect();
 
     let opts = crate::build::binary::BinaryMetadataOptions {
         profiles,
         vendor,
-        parallel: crate::build::env::num_parallel(),
-        source_date_epoch,
+        exported_env,
         build_arch,
         host_arch,
     };