Fixed shebang kernel limitation with virtualenv during test run (https://github.com/pypa/virtualenv/issues/596)

Change-Id: I5a7868c76fa512eaaa10aa1b5a2a7756516a37cc
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index 9a4e8ea..af5ccb3 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -37,7 +37,7 @@
     log_info "Setting up Python virtualenv"
     virtualenv $VENV_DIR
     source ${VENV_DIR}/bin/activate
-    pip install salt${PIP_SALT_VERSION}
+    python -m pip install salt${PIP_SALT_VERSION}
 }
 
 setup_pillar() {
@@ -114,7 +114,7 @@
 
 salt_run() {
     [ -e ${VENV_DIR}/bin/activate ] && source ${VENV_DIR}/bin/activate
-    salt-call ${SALT_OPTS} $*
+    python $(which salt-call) ${SALT_OPTS} $*
 }
 
 prepare() {