Permit space-separated XS-Go-Import-Path

For example:

    XS-Go-Import-Path:
     example.com/foo
     example.com/bar

This avoids forcing package maintainers to look up whether a trailing
comma after the final item is allowed or not.  (Separating by
whitespace or permitting a trailing comma makes it easier to construct
a readable and VC-friendly multiline list of values.)  Spaces cannot
exist in a module path, so there is no risk of parsing ambiguity.

The `make` subcommand doesn't produce space-separated lists, and
`dh-golang` doesn't yet support it, so this is just a step towards
generally allowing it everywhere.

Author: rhansen

search.go

@@ -26,6 +26,9 @@ type ftpMasterApiResult struct {
 	Source        string `json:"source"`
 }
 
+// Entries in XS-Go-Import-Path are separated by commas and/or spaces.
+var listSep = regexp.MustCompile(`[,\s]+`)
+
 type getGolangBinariesConfig struct {
 	url string
 }
@@ -61,13 +64,9 @@ func getGolangBinaries(opts ...getGolangBinariesOption) (map[string]debianPackag
 		if !strings.HasSuffix(pkg.Binary, "-dev") {
 			continue // skip -dbgsym packages etc.
 		}
-		for _, importPath := range strings.Split(pkg.MetadataValue, ",") {
-			// XS-Go-Import-Path can be comma-separated and contain spaces.
-			importPath := strings.TrimSpace(importPath)
-			// importPath might be the empty string if XS-Go-Import-Path has a leading comma, trailing
-			// comma, or extraneous internal comma.  It might also be empty if api.ftp-master.d.o returns
-			// packages where XS-Go-Import-Path is explicitly set to the empty string or to a
-			// whitespace-only string.
+		for _, importPath := range listSep.Split(pkg.MetadataValue, -1) {
+			// importPath might be the empty string if XS-Go-Import-Path has a leading or trailing
+			// listSep, or the entire string matches listSep*.
 			if importPath == "" {
 				continue
 			}

search_test.go

@@ -165,6 +165,24 @@ func TestGetGolangBinaries(t *testing.T) {
 				},
 			},
 		},
+		{
+			desc: "whitespace separated",
+			results: []ftpMasterApiResult{{
+				Binary:        "golang-example-foo-dev",
+				MetadataValue: "example.com/foo \n\texample.com/bar",
+				Source:        "golang-example-foo",
+			}},
+			want: map[string]debianPackage{
+				"example.com/foo": {
+					binary: "golang-example-foo-dev",
+					source: "golang-example-foo",
+				},
+				"example.com/bar": {
+					binary: "golang-example-foo-dev",
+					source: "golang-example-foo",
+				},
+			},
+		},
 	} {
 		t.Run(tc.desc, func(t *testing.T) {
 			t.Parallel()