Merge branch 'bl/pretty-shorthand-config-fix'

The "--pretty=<shortHand>" option of the commands in the "git log"
family, defined as "[pretty] shortHand = <expansion>" should have
been looked up case insensitively, but was not, which has been
corrected.

* bl/pretty-shorthand-config-fix:
  pretty: find pretty formats case-insensitively
  pretty: update tests to use `test_config`

diff --cc pretty.c
Simple merge

diff --cc t/t4205-log-pretty-formats.sh
Simple merge