Remove generator cache directory if it failed

If the generator invocation failed for any reason, its output directory
is removed. While this is bad for debugging failing generators, it at
least prevents the next FuseSoC-run to assume, that the generator was
successful and hence a failed generator is retried on the next FuseSoC
run. Since the stderr of the executed command is printed to the user,
the harm for debugging is not that large, so this should be fine.

As an alternative, one could store a file `.success` (or similar) in the
generator directory and only use the cache directory if that file is
present there.

fusesoc/edalizer.py

@@ -672,7 +672,17 @@ def generate(self):
                 )
             else:
                 shutil.rmtree(generator_cwd, ignore_errors=True)
-            self._run(generator_cwd)
+            try:
+                self._run(generator_cwd)
+            except:
+                # If the generator invocation failed for any reason, its output
+                # directory is removed. While this is bad for debugging failing
+                # generators, it at least prevents the next FuseSoC-run to
+                # assume, that the generator was successful and hence a failed
+                # generator is retried on the next FuseSoC-run.
+                logger.debug("Generator failed, removing its output files")
+                shutil.rmtree(generator_cwd, ignore_errors=False)
+                raise
             # TODO: Release cache lock
 
         cores = []