A test was changing directory and then incorrectly restoring the directory

to the "testdir" which is the build directory for that test, not the
original source directory.  That caused subsequent tests to fail.

Author: jimingham

lldb/test/API/commands/process/attach/TestProcessAttach.py

@@ -74,7 +74,8 @@ def test_attach_to_process_from_different_dir_by_id(self):
         popen = self.spawnSubprocess(exe)
 
         os.chdir(newdir)
-        self.addTearDownHook(lambda: os.chdir(testdir))
+        sourcedir = self.getSourceDir()
+        self.addTearDownHook(lambda: os.chdir(sourcedir))
         self.runCmd("process attach -p " + str(popen.pid))
 
         target = self.dbg.GetSelectedTarget()