fix(core): add a workaround for potential bugs in git hasher (#3521)

Author: vsavkin

Diff for: packages/workspace/src/core/hasher/git-hasher.ts

@@ -1,4 +1,6 @@
 import { spawnSync } from 'child_process';
+import { join } from 'path';
+import { statSync } from 'fs';
 
 function parseGitLsTree(output: string): Map<string, string> {
   const changes: Map<string, string> = new Map<string, string>();
@@ -102,8 +104,39 @@ function gitStatus(
       deletedFiles.push(filename);
     }
   });
-  const status = getGitHashForFiles(filesToHash, path);
-  return { deletedFiles, status };
+
+  const updated = checkForDeletedFiles(path, filesToHash, deletedFiles);
+  const status = getGitHashForFiles(updated.filesToHash, path);
+  return { deletedFiles: updated.deletedFiles, status };
+}
+
+/**
+ * This is only needed because of potential issues with interpreting "git status".
+ * We had a few issues where we didn't interpret renames correctly. Even though
+ * doing this somewhat slow, we will keep it for now.
+ *
+ * @vsavkin remove it in nx 10.2
+ */
+function checkForDeletedFiles(
+  path: string,
+  files: string[],
+  deletedFiles: string[]
+) {
+  let filesToHash = [];
+
+  files.forEach((f) => {
+    try {
+      statSync(join(path, f)).isFile();
+      filesToHash.push(f);
+    } catch (err) {
+      console.warn(
+        `Warning: Fell back to using 'fs' to identify ${f} as deleted. Please open an issue at https://github.com/nrwl/nx so we can investigate.`
+      );
+      deletedFiles.push(f);
+    }
+  });
+
+  return { filesToHash, deletedFiles };
 }
 
 export function getFileHashes(path: string): Map<string, string> {