Trick the srcs_test to regenerate the list of sources at every change of the workspace

We need to declare a dependency on something that change every time the workspace change or we get false negative failure.

PiperOrigin-RevId: 166327024
diff --git a/src/test/shell/bazel/list_source_repository.bzl b/src/test/shell/bazel/list_source_repository.bzl
index f0900ab..bb19a60 100644
--- a/src/test/shell/bazel/list_source_repository.bzl
+++ b/src/test/shell/bazel/list_source_repository.bzl
@@ -21,6 +21,13 @@
 def _impl(rctx):
   workspace = rctx.path(Label("//:BUILD")).dirname
   srcs_excludes = "XXXXXXXXXXXXXX1268778dfsdf4"
+  # Depending in ~/.git/logs/HEAD is a trick to depends on something that
+  # change everytime the workspace content change.
+  r = rctx.execute(["test", "-f", "%s/.git/logs/HEAD" % workspace])
+  if r.return_code == 0:
+    # We only add the dependency if it exists.
+    unused_var = rctx.path(Label("//:.git/logs/HEAD"))  # pylint: disable=unused-variable
+
   if "SRCS_EXCLUDES" in rctx.os.environ:
     srcs_excludes = rctx.os.environ["SRCS_EXCLUDES"]
   r = rctx.execute(["find", str(workspace), "-type", "f"])