internal/fetchdatasource: ignore latest-version errors

A FetchDataSource may be configured with a proxy for latest-version
information while still being used for local modules. So ignore
latest-version errors.

For golang/go#47780

Change-Id: I30448e133faec80002194df59e6f2db449f80625
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/345249
Trust: Jonathan Amsterdam <jba@google.com>
Run-TryBot: Jonathan Amsterdam <jba@google.com>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jamal Carvalho <jamal@golang.org>
Reviewed-by: Julie Qiu <julie@golang.org>

1 files changed, 5 insertions, 6 deletions

diff --git a/internal/fetchdatasource/fetchdatasource.go b/internal/fetchdatasource/fetchdatasource.go
index 896899d5..69f803eb 100644
--- a/internal/fetchdatasource/fetchdatasource.go
+++ b/internal/fetchdatasource/fetchdatasource.go
@@ -103,16 +103,15 @@ func (ds *FetchDataSource) getModule(ctx context.Context, modulePath, version st
 	m, err := ds.fetch(ctx, modulePath, version)
 	if m != nil && ds.opts.ProxyClientForLatest != nil {
 		// Use the go.mod file at the raw latest version to fill in deprecation
-		// and retraction information.
-		lmv, err2 := fetch.LatestModuleVersions(ctx, modulePath, ds.opts.ProxyClientForLatest, nil)
-		if err2 != nil {
-			err = err2
-		} else {
+		// and retraction information. Ignore any problems getting the
+		// information, because we may be trying to do this for a local module
+		// that the proxy doesn't know about.
+		if lmv, err := fetch.LatestModuleVersions(ctx, modulePath, ds.opts.ProxyClientForLatest, nil); err == nil {
 			lmv.PopulateModuleInfo(&m.ModuleInfo)
 		}
 	}
 
-	// Don't cache cancellations.
+	// Cache both successes and failures, but not cancellations.
 	if !errors.Is(err, context.Canceled) {
 		ds.cachePut(modulePath, version, m, err)
 	}