safehasattr: pass attribute name as string instead of bytes
This is a step toward replacing `util.safehasattr` usage with plain `hasattr`.
The builtin function behave poorly in Python2 but this was fixed in Python3.
These change are done one by one as they tend to have a small odd to trigger
puzzling breackage.
missing lfs pointer keys: oid, size
ok
unexpected lfs pointer value: version='https://unknown.github.com/spec/v1'
cannot parse git-lfs text: 'version https://git-lfs.github.com/spec/v1\n\noid sha256:4d7a214614ab2935c943f9e0ff69d22eadbb8f32b1258daaa5e2ca24d17e2393\nsize 12345\nx-foo extra-information\n'
unexpected lfs pointer value: oid='ahs256:4d7a214614ab2935c943f9e0ff69d22eadbb8f32b1258daaa5e2ca24d17e2393'
unexpected lfs pointer value: oid='4d7a214614ab2935c943f9e0ff69d22eadbb8f32b1258daaa5e2ca24d17e2393'
unexpected lfs pointer value: size='0x12345'
ok
cannot parse git-lfs text: 'version https://git-lfs.github.com/spec/v1\noid sha256:4d7a214614ab2935c943f9e0ff69d22eadbb8f32b1258daaa5e2ca24d17e2393\nsize 12345\nx-foo extra\ninformation\n'
unexpected lfs pointer key: x_foo
missing lfs pointer keys: oid
missing lfs pointer keys: oid, size