Factor some 0000... blank refs

Behavior changes:

- it was impossible to push to protected branches if the new commit
  SHA started with 7 zeros. Fixed due to the change to git_access

- events showed 8 zeros, but the standard Git abbreviation is to use 7,
  so now 7 are used.

Missing newlines got added because of perl refactoring on `000000000000000000`
Line is too long. [95/80]