Cancel usage of chunk_number if loading the whole dependency

[dachengx]

What is the problem / what does the code in this PR do

To make the lineage unchanged after merging per-chunk storage, we need to set chunk_number to None to keep lineage hash the same as non-per-chunk storage.

Can you briefly describe how it works?

Can you give a minimal working example (or illustrate with a figure)?

Please include the following if applicable:

• Update the docstring(s)
• Update the documentation
• Tests to check the (new) code is working as desired.
• Does it solve one of the open issues on github?

Please make sure that all automated tests have passed before asking for a review (you can save the PR as a draft otherwise).

[coveralls]

coverage: 90.331% (-0.01%) from 90.342%
when pulling 805adcb on cancel_chunk_number
into 4b823ac on master.