git-arc: Do not echo unescaped literals to jq

[jlduran_gmail.com]

Summary

Store the json blobs in temporary files instead of variables, and feed
them to jq for parsing.

When echoing "\n", the new line will become a literal new line, and
therefore, invalid json input:

jq: parse error: Invalid string: control characters from U+0000 through U+001F must be escaped ...

To reproduce:

% git arc patch -c D12345

[jlduran_gmail.com]

I'm not a big fan of making temporary files, but I don't know how else to fix it.

[imp]

I think this looks good

[jlduran_gmail.com]

Thank you.. Hmm I am pretty sure I included @emaste in the review. Well, still learning git-arc.

[markj]

Looks ok to me, thank you.

[jlduran_gmail.com]

I think I know how to achieve the same result using printf, and escaping literals with %s.
Regardless, I only have one more patch for git-arc (git arc list) that may benefit of review_data being in a file. If it turns out otherwise, I can "revert" to using variables.
I'm done trying out this great article on the topic.
Thank you for the reviews!

[markj]

In D46767#1066872, @jlduran_gmail.com wrote:

I think I know how to achieve the same result using printf, and escaping literals with %s.
Regardless, I only have one more patch for git-arc (git arc list) that may benefit of review_data being in a file. If it turns out otherwise, I can "revert" to using variables.
I'm done trying out this great article on the topic.
Thank you for the reviews!

I think using files is fine. We don't care about the cost of creating a few extra temporary files here.