Fix bare 'except:' to placate errors in new flake8 version.

- fixes E722 errors from latest version of flake8
- requires us to not use 'bare except:' and catch BaseException instead

var/spack/repos/builtin/packages/charm/package.py

@@ -177,6 +177,6 @@ def install(self, spec, prefix):
                         shutil.copy2(filepath, tmppath)
                         os.remove(filepath)
                         os.rename(tmppath, filepath)
-                    except:
+                    except (IOError, OSError):
                         pass
         shutil.rmtree(join_path(prefix, "tmp"))