Fix a bug in lldb-dotest that was uncovered by setting no value for dotest_args_str.

We were splitting the string, and adding that array to cmd.  But split generated
[''] which shows up later on as an empty "test directory search path".  That got
extended to the CWD + "" which generally doesn't have any tests, so

lldb-dotest -p SomeRealTest.py

would fail with a no matching tests error.

Differential Revision: https://reviews.llvm.org/D133075

Author: jimingham

lldb/utils/lldb-dotest/lldb-dotest.in

@@ -16,7 +16,11 @@ llvm_tools_dir = "@LLVM_TOOLS_DIR_CONFIGURED@"
 
 if __name__ == '__main__':
     wrapper_args = sys.argv[1:]
-    dotest_args = dotest_args_str.split(';')
+    dotest_args = []
+    # split on an empty string will produce [''] and if you
+    # add that to the command, it will be treated as a directory...
+    if len(dotest_args_str) > 0:
+        dotest_args = dotest_args_str.split(';')
     # Build dotest.py command.
     cmd = [sys.executable, dotest_path]
     cmd.extend(['--arch', arch])