Merge branch 'vr/use-our-perl-in-tests' into maint

Some implementations of Perl terminates "lines" with CRLF even when
the script is operating on just a sequence of bytes.  Make sure to
use "$PERL_PATH", the version of Perl the user told Git to use, in
our tests to avoid unnecessary breakages in tests.

* vr/use-our-perl-in-tests:
t/README: add a bit more Don'ts
tests: enclose $PERL_PATH in double quotes
t/test-lib.sh: export PERL_PATH for use in scripts
t: Replace 'perl' by $PERL_PATH

diff --combined t/t9300-fast-import.sh
index c17f52e586747198a74323b578a654edec436f57,11f977bec2e3b913a4beed59643be01ccad86435..2fcf2694696fedb5e7e3d57c869f7dbbbf23dbec
--- 1/t/t9300-fast-import.sh
--- 2/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@@ -12,7 -12,7 +12,7 @@@ test_description='test git fast-import 
  # This could be written as "head -c $1", but IRIX "head" does not
  # support the -c option.
  head_c () {
-       perl -e '
+       "$PERL_PATH" -e '
                my $len = $ARGV[1];
                while ($len > 0) {
                        my $s;
@@@ -2117,7 -2117,7 +2117,7 @@@ test_expect_success 
      grep :1 git.marks'
  
  test_expect_success \
 -    'R: export-marks options can be overriden by commandline options' \
 +    'R: export-marks options can be overridden by commandline options' \
      'cat input | git fast-import --export-marks=other.marks &&
      grep :1 other.marks'