fix: abort renovation if repository has changed during run

If attempting to create a branch and it already exists, or attempting to update a branch and it no longer exists, then we abort.

lib/platform/github/index.js

@@ -1009,13 +1009,14 @@ async function createBranch(branchName, sha) {
     config.branchList.push(branchName);
     await get.post(`repos/${config.repository}/git/refs`, options);
   } catch (err) /* istanbul ignore next */ {
-    if (err.statusCode === 422) {
-      logger.warn('Branch already existed? Attempting update instead');
-      await updateBranch(branchName, sha);
-    } else {
-      logger.debug('Unknown error creating branch');
-      throw err;
+    if (
+      err.statusCode === 422 &&
+      err.message.startsWith('Reference already exists')
+    ) {
+      logger.info({ err }, 'Branch already exists - exiting');
+      throw new Error('repository-changed');
     }
+    throw err;
   }
 }
 
@@ -1032,10 +1033,21 @@ async function updateBranch(branchName, commit) {
   if (config.forkToken) {
     options.token = config.forkToken;
   }
+  try {
     await get.patch(
       `repos/${config.repository}/git/refs/heads/${branchName}`,
       options
     );
+  } catch (err) /* istanbul ignore next */ {
+    if (
+      err.statusCode === 422 &&
+      err.message.startsWith('Reference does not exist')
+    ) {
+      logger.info({ err }, 'Branch no longer exists - exiting');
+      throw new Error('repository-changed');
+    }
+    throw err;
+  }
 }
 
 // Low-level commit operations

lib/workers/branch/index.js

@@ -158,6 +158,11 @@ async function processBranch(branchConfig) {
       config.forcePr = true;
     }
   } catch (err) {
+    // istanbul ignore if
+    if (err.message === 'repository-changed') {
+      logger.debug('Passing repository-changed error up');
+      throw err;
+    }
     logger.error({ err }, `Error updating branch: ${err.message}`);
     // Don't throw here - we don't want to stop the other renovations
     return 'error';

lib/workers/repository/error.js

@@ -30,6 +30,10 @@ async function handleError(config, err) {
   } else if (err.message === 'loops>5') {
     logger.warn('Repository has looped 5 times already');
     return err.message;
+  } else if (err.message === 'repository-changed') {
+    logger.warn('Repository has changed during renovation - aborting');
+    delete config.branchList; // eslint-disable-line no-param-reassign
+    return err.message;
   } else if (err.message === 'config-validation') {
     delete config.branchList; // eslint-disable-line no-param-reassign
     logger.info({ error: err }, 'Repository has invalid config');

test/workers/repository/error.spec.js

@@ -13,6 +13,7 @@ describe('workers/repository/error', () => {
     const errors = [
       'uninitiated',
       'disabled',
+      'repository-changed',
       'fork',
       'no-package-files',
       'loops>5',