switched coverage to native go test

.gitignore

@@ -4,5 +4,5 @@
 playground/
 kopia-*.tar.gz
 kopia-*.zip
-combined.cov
+*.cov
 .vscode/

Makefile

@@ -90,4 +90,9 @@ godoc:
 	godoc -http=:33333
 
 coverage:
-	./coverage.sh
+	test --coverprofile tmp.cov github.com/kopia/kopia/...
+	go tool cover -html=tmp.cov
+
+coverage-repo:
+	go test --coverprofile tmp.cov github.com/kopia/kopia/block/... github.com/kopia/kopia/object/... github.com/kopia/kopia/repo/...
+	go tool cover -html=tmp.cov

coverage.sh

@@ -1,8 +0,0 @@
-echo mode: set > combined.cov
-for p in `go list github.com/kopia/kopia/...`; do
-    go test --coverprofile tmp.cov $p
-    grep -v "mode: " tmp.cov >> combined.cov
-    rm tmp.cov
-done
-go tool cover -html=combined.cov
-rm combined.cov