Add a new test checking the command substitution

substitution/main.fmf

@@ -0,0 +1,4 @@
+summary: Verify correct $$ parsing in command substitution
+description: |
+    Parsing commands break when using $$ in command substitution $(..).
+    Test for https://bugzilla.redhat.com/show_bug.cgi?id=1727952

substitution/runtest.sh

@@ -0,0 +1,46 @@
+#!/bin/bash
+# vim: dict+=/usr/share/beakerlib/dictionary.vim cpt=.,w,b,u,t,i,k
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+#
+#   Author: Karel Volný <kvolny@redhat.com>
+#   Copyright (c) 2019 Red Hat, Inc.
+#
+#   This program is free software: you can redistribute it and/or
+#   modify it under the terms of the GNU General Public License as
+#   published by the Free Software Foundation, either version 2 of
+#   the License, or (at your option) any later version.
+#
+#   This program is distributed in the hope that it will be
+#   useful, but WITHOUT ANY WARRANTY; without even the implied
+#   warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+#   PURPOSE.  See the GNU General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License
+#   along with this program. If not, see http://www.gnu.org/licenses/.
+#
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+# Include Beaker environment
+. /usr/share/beakerlib/beakerlib.sh || exit 1
+
+PACKAGES=${PACKAGES:-bash}
+
+rlJournalStart
+    rlPhaseStartSetup
+        rlAssertRpm --all
+        rlRun "TmpDir=\$(mktemp -d)" 0 "Creating tmp directory"
+        rlRun "pushd $TmpDir"
+    rlPhaseEnd
+
+    rlPhaseStartTest
+        rlRun "touch testfile" 0 "Creating the test file"
+        rlRun -s "A=\$(awk -v p=\$\$ '{print \$0}' <testfile)" 0 "Running the reproducer"
+        rlAssertNotGrep "Usage" $rlRun_LOG
+    rlPhaseEnd
+
+    rlPhaseStartCleanup
+        rlRun "popd"
+        rlRun "rm -r $TmpDir" 0 "Removing tmp directory"
+    rlPhaseEnd
+rlJournalPrintText
+rlJournalEnd