hotfix Drone install Horovod (#4038)

* hotfix Drone install Horovod

* notes

.drone.yml

@@ -27,8 +27,7 @@ steps:
     CODECOV_TOKEN:
       from_secret: codecov_token
     MKL_THREADING_LAYER: GNU
-    HOROVOD_GPU_ALLREDUCE: NCCL
-    HOROVOD_GPU_BROADCAST: NCCL
+    HOROVOD_GPU_OPERATIONS: NCCL
     HOROVOD_WITH_PYTORCH: 1
     HOROVOD_WITHOUT_TENSORFLOW: 1
     HOROVOD_WITHOUT_MXNET: 1
@@ -41,6 +40,9 @@ steps:
   #    path: /opt/conda/lib/python3.7/site-packages
 
   commands:
+    # todo: remove unsets as in correct image Horovod shall be set
+    - unset HOROVOD_GPU_ALLREDUCE
+    - unset HOROVOD_GPU_BROADCAST
     - export PATH="$PATH:/root/.local/bin"
     - python --version
     - pip install pip -U
@@ -48,8 +50,8 @@ steps:
     - nvidia-smi
     #- bash ./requirements/install_AMP.sh
     - apt-get update && apt-get install -y cmake
-    - pip install -r ./requirements/base.txt --user -q --upgrade-strategy only-if-needed
-    - pip install -r ./requirements/devel.txt --user -q --upgrade-strategy only-if-needed
+    - pip uninstall -y horovod  # todo: this shall not be needed
+    - pip install -r ./requirements/devel.txt --user -q --upgrade-strategy only-if-needed  --no-cache-dir
     #- pip install -r ./requirements/docs.txt --user -q
     - pip install -r ./requirements/examples.txt --user -q --upgrade-strategy only-if-needed
     - pip list

pytorch_lightning/utilities/argparse_utils.py

@@ -24,11 +24,9 @@ def from_argparse_args(cls, args: Union[Namespace, ArgumentParser], **kwargs):
         >>> args = Trainer.parse_argparser(parser.parse_args(""))
         >>> trainer = Trainer.from_argparse_args(args, logger=False)
     """
-    # fist check if any args are defined in environment for the class and set as default
-
     if isinstance(args, ArgumentParser):
         args = cls.parse_argparser(args)
-    # if other arg passed,  update parameters
+
     params = vars(args)
 
     # we only want to pass in valid Trainer args, the rest may be user specific