Merge pull request #6890 from habitat-sh/retry_err

report last error after all failed pkg download attempts

.expeditor/scripts/shared.ps1

@@ -1,3 +1,17 @@
+function Get-RustfmtToolchain {
+  # It turns out that every nightly version of rustfmt has slight tweaks from the previous version.
+  # This means that if we're always using the latest version, then we're going to have enormous
+  # churn. Even PRs that don't touch rust code will likely fail CI, since master will have been
+  # formatted with a different version than is running in CI. Because of this, we're going to pin
+  # the version of nightly that's used to run rustfmt and bump it when we do a new release.
+  #
+  # Note that not every nightly version of rust includes rustfmt. Sometimes changes are made that
+  # break the way rustfmt uses rustc. Therefore, before updating the pin below, double check
+  # that the nightly version you're going to update it to includes rustfmt. You can do that
+  # using https://mexus.github.io/rustup-components-history/x86_64-unknown-linux-gnu.html
+  Get-Content "$PSScriptRoot\..\..\RUSTFMT_VERSION"
+}
+
 function Install-Habitat {
   if (get-command -Name hab -ErrorAction SilentlyContinue) {
       Write-Host "Using habitat version:`n$(hab --version)"

components/common/src/command/package/install.rs

@@ -672,11 +672,12 @@ impl<'a> InstallTask<'a> {
                    ident);
         } else if self.is_offline() {
             return Err(Error::OfflineArtifactNotFound(ident.as_ref().clone()));
-        } else if retry(delay::Fixed::from(RETRY_WAIT).take(RETRIES), fetch_artifact).is_err() {
+        } else if let Err(err) = retry(delay::Fixed::from(RETRY_WAIT).take(RETRIES), fetch_artifact)
+        {
             return Err(Error::DownloadFailed(format!("We tried {} times but \
                                                       could not download {}. \
-                                                      Giving up.",
-                                                     RETRIES, ident)));
+                                                      Last error was: {}",
+                                                     RETRIES, ident, err)));
         }
 
         let mut artifact = PackageArchive::new(self.cached_artifact_path(ident));