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

Change-Id: I5cf3041e4cfd883c19f3996d23a9a7113a5feae4
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index 0d29e9d..25e5125 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -39,8 +39,8 @@
     log_info "Setting up Python virtualenv"
     virtualenv $VENV_DIR
     source ${VENV_DIR}/bin/activate
-    pip install salt${PIP_SALT_VERSION}
-    pip install reno
+    python -m pip install salt${PIP_SALT_VERSION}
+    python -m pip install reno
 }
 
 setup_mock_bin() {
@@ -126,7 +126,7 @@
 
 salt_run() {
     [ -e ${VENV_DIR}/bin/activate ] && source ${VENV_DIR}/bin/activate
-    salt-call ${SALT_OPTS} $*
+    python $(which salt-call) ${SALT_OPTS} $*
 }
 
 prepare() {