Merge branch 'rs/grep-parser-fix'

"git grep --and -e foo" ought to have been diagnosed as an error
but instead segfaulted, which has been corrected.

* rs/grep-parser-fix:
  grep: report missing left operand of --and

diff --cc grep.c
Simple merge

diff --cc t/t7810-grep.sh
index 5830733f3d25be77cc4318e76d9c30695d4adbd0,47434e668713ab5c8b37e5a23513c7eea142fc7a..6b6423a07c3a6e0b497e3fbd109679b38dbe3856
--- 1/t/t7810-grep.sh
--- 2/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@@ -6,11 -6,15 +6,18 @@@
  test_description='git grep various.
  '
  
 +GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 +export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 +
  . ./test-lib.sh
  
+ test_invalid_grep_expression() {
+       params="$@" &&
+       test_expect_success "invalid expression: grep $params" '
+               test_must_fail git grep $params -- nonexisting
+       '
+ }
+ 
  cat >hello.c <<EOF
  #include <assert.h>
  #include <stdio.h>