git-arc: Use printf instead of echo

[0mp]

Summary

Some shell implementations other than FreeBSD's sh(1) do not handle
handle passing complex strings to echo. For example,
git arc create HEAD works with macOS' sh(1) but
git arc patch -c D12345 would error out with:

jq: parse error: Invalid string: control characters from U+0000 through U+001F must be escaped at line 27, column 57

Fix that by using printf consistently across git-arc(1).

MFC after: 2 weeks

Test Plan

I've been using printfs in git-arc for some time now when I use git-arc(1) on macOS.

[des]

revert everything except the three places I commented

tools/tools/git/git-arc.sh

331

no -n needed here

447

keep this

464

[jlduran]

Thank you for making this tool more portable. This is a cousin commit of D46781 and D46767. I agree, echo (without -n is portable) and IMO, more readable than printf, because there is no need to add a new line at the end. The issue is only with echo -n.

[0mp]

In D47274#1077940, @jlduran_gmail.com wrote:

Thank you for making this tool more portable. This is a cousin commit of D46781 and D46767. I agree, echo (without -n is portable) and IMO, more readable than printf, because there is no need to add a new line at the end. The issue is only with echo -n.

Amazing work! I've not seen those patches earlier! I'll review and commit them.

[0mp]

I'm closing this revision as I landed @jlduran_gmail.com's patches instead:

• https://reviews.freebsd.org/D46781
• https://reviews.freebsd.org/D46767