Unblock stable build around policies (microsoft#157608)

Author: bpasero

build/lib/policies.js

@@ -438,8 +438,20 @@ async function getNLS(resourceUrlTemplate, languageId, version) {
     }
     catch (err) {
         if (/\[404\]/.test(err.message)) {
-            console.warn(`Language pack ${languageId}@${version} is missing. Downloading previous version...`);
-            return await getSpecificNLS(resourceUrlTemplate, languageId, previousVersion(version));
+            const thePreviousVersion = previousVersion(version);
+            console.warn(`Language pack ${languageId}@${version} is missing. Downloading previous version ${thePreviousVersion}...`);
+            try {
+                return await getSpecificNLS(resourceUrlTemplate, languageId, thePreviousVersion);
+            }
+            catch (err) {
+                if (/\[404\]/.test(err.message)) {
+                    console.warn(`Language pack ${languageId}@${thePreviousVersion} is missing. Downloading previous version...`);
+                    return await getSpecificNLS(resourceUrlTemplate, languageId, previousVersion(thePreviousVersion));
+                }
+                else {
+                    throw err;
+                }
+            }
         }
         else {
             throw err;

build/lib/policies.ts

@@ -622,8 +622,18 @@ async function getNLS(resourceUrlTemplate: string, languageId: string, version:
 		return await getSpecificNLS(resourceUrlTemplate, languageId, version);
 	} catch (err) {
 		if (/\[404\]/.test(err.message)) {
-			console.warn(`Language pack ${languageId}@${version} is missing. Downloading previous version...`);
-			return await getSpecificNLS(resourceUrlTemplate, languageId, previousVersion(version));
+			const thePreviousVersion = previousVersion(version);
+			console.warn(`Language pack ${languageId}@${version} is missing. Downloading previous version ${thePreviousVersion}...`);
+			try {
+				return await getSpecificNLS(resourceUrlTemplate, languageId, thePreviousVersion);
+			} catch (err) {
+				if (/\[404\]/.test(err.message)) {
+					console.warn(`Language pack ${languageId}@${thePreviousVersion} is missing. Downloading previous version...`);
+					return await getSpecificNLS(resourceUrlTemplate, languageId, previousVersion(thePreviousVersion));
+				} else {
+					throw err;
+				}
+			}
 		} else {
 			throw err;
 		}