tests/histedit-helpers.sh

tests: convert the 'file://\$TESTTMP' rule to an automatic substitution

The rule only triggered on non Windows platforms, even though Windows also
required an adjustment.  Automatic seems better.

The aggressive globbing in test-subrepo-svn.t was found and rewritten by the
substitution.

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
}