[PATCH v3 0/3] fix `sudo make install` regression in maint

Changes since RFC v3:
* Cleaner split of tests so patch1 will not break if called under sudo
  and will be less likely to break any CI by restricting its runs to
  IKNOWWHATIAMDOING=YES
* Simplified patch3 with all requested enhancements, except that it is
  still keeping the (currently unused) possibility to override the shell
  used in run_with_sudo with an optional first parameter.

Carlo Marcelo Arenas Belón (3):
  t: document regression git safe.directory when using sudo
  git-compat-util: avoid failing dir ownership checks if running
    privileged
  t0034: enhance framework to allow testing more commands under sudo

 Documentation/config/safe.txt  |   9 +++
 git-compat-util.h              |  40 +++++++++++-
 t/lib-sudo.sh                  |  13 ++++
 t/t0034-root-safe-directory.sh | 115 +++++++++++++++++++++++++++++++++
 4 files changed, 176 insertions(+), 1 deletion(-)
 create mode 100644 t/lib-sudo.sh
 create mode 100755 t/t0034-root-safe-directory.sh

A range-diff against RFC v3 shown below to easy review:

1:  51d0d485b5f ! 1:  27192634476 t: document regression git safe.directory when using sudo
    @@ t/t0034-root-safe-directory.sh (new)
     +
     +. ./test-lib.sh
     +
    ++if [ "$IKNOWWHATIAMDOING" != "YES" ]
    ++then
    ++	skip_all="You must set env var IKNOWWHATIAMDOING=YES in order to run this test"
    ++	test_done
    ++fi
    ++
     +# this prerequisite should be added to all the tests, it not only prevents
     +# the test from failing but also warms up any authentication cache sudo
     +# might need to avoid asking for a password
    @@ t/t0034-root-safe-directory.sh (new)
     +	)
     +'
     +
    -+# this MUST be always the last test
    ++# this MUST be always the last test, if used more than once, the next
    ++# test should do a full setup again.
     +test_expect_success SUDO 'cleanup' '
     +	sudo rm -rf root
     +'
2:  4928ad698e2 = 2:  58b4671b9ef git-compat-util: avoid failing dir ownership checks if running privileged
3:  98aae872efd < -:  ----------- t0034: enhance framework to allow testing more commands under sudo
-:  ----------- > 3:  7c029c66666 t0034: enhance framework to allow testing more commands under sudo

Albeit not ideal, if needef patches 1 and 2 could be fastracked to close the regression while patch 3 goes through further iterations.

Carlo