Checking whether the output is a tty is done before checking whether the pager was on, so colours were wrong for some setups

Dependencies

• [2] 5BB266P6 Optional colours in the global config file
• [3] ZRUPLBBT Colours in diff and change: separating concerns and dependencies
• [*] SXEYMYF7 Fixing the bad changes in history (unfortunately, by rebooting).

Change contents

• replacement in pijul/src/commands/diff.rs at line 263
  [2.905]→[2.905:939](∅→∅)
  − colors |= super::pager();
  [2.905]

  [3.2096]
  + colors &= super::pager();