tests/histedit-helpers.sh

tests: make directory to prevent test process from going out of $TESTTMP

Before this patch, test process for test-bookmarks.t goes out of
$TESTTMP at "cd .." before creation of "orderrepo" repository.

To prevent test process from going out of $TESTTMP, this patch makes
directory "repo" sub-directory and executes almost all test scenarios
in test-bookmarks.t under it.

This is preparation for new test added in subsequent patch.

fixbundle() {
    grep -v 'saving bundle' | grep -v 'saved backup' | \
        grep -v added | grep -v adding | \
        grep -v "unable to find 'e' for patching" | \
        grep -v "e: No such file or directory" | \
    cat
}