Repository: pykeen/pykeen
Issue: Index out of range in PyTorch embedding using own data
Root cause: Validation Gap

**Describe the bug**
I am trying to use pykeen on my own data and following the BYOD section of the docs I am doing the following:
```
from pykeen.triples import TriplesFactory
from pykeen.pipeline import pipeline

tf = TriplesFactory(path="/tmp/exampledata.txt")
training, testing = tf.split()

pipeline_result = pipeline(
    training_triples_factory=training, testing_triples_factory=testing, model="TransH"
)
```

Unfortunately I get the following:
```
Using random_state=1333753659 to split TriplesFactory(path="/tmp/out")
No random seed is specified. Setting to 2098687070.
No cuda devices were available. The model runs on CPU
Training epochs on cpu:   0%|                                                           | 0/5 [00:00<?, ?epoch/s]INFO:pykeen.training.training_loop:using stopper: <pykeen.stoppers.stopper.NopStopper object at 0x7f42e4842cc0>
Training epochs on cpu:   0%|                                                           | 0/5 [00:00<?, ?epoch/s]
Traceback (most recent call last):                                                                               
  File "test.py", line 8, in <module>
    training_triples_factory=training, testing_triples_factory=testing, model="TransH"
  File "/home/dobraczka/.local/share/virtualenvs/embedding-transformers-I3i1Obsv/lib/python3.7/site-packages/pykeen/pipeline.py", line 815, in pipeline
    **training_kwargs,
  File "/home/dobraczka/.local/share/virtualenvs/embedding-transformers-I3i1Obsv/lib/python3.7/site-packages/pykeen/training/training_loop.py", line 190, in train
    num_workers=num_workers,
  File "/home/dobraczka/.local/share/virtualenvs/embedding-transformers-I3i1Obsv/lib/python3.7/site-packages/pykeen/training/training_loop.py", line 376, in _train
    slice_size,
  File "/home/dobraczka/.local/share/virtualenvs/embedding-transformers-I3i1Obsv/lib/python3.7/site-packages/pykeen/training/training_loop.py", line 438, in _forward_pass
    slice_size=slice_size,
  File "/home/dobraczka/.local/share/virtualenvs/embedding-transformers-I3i1Obsv/lib/python3.7/site-packages/pykeen/training/slcwa.py", line 101, in _process_batch
    positive_scores = self.model.score_hrt(positive_batch)
  File "/home/dobraczka/.local/share/virtualenvs/embedding-transformers-I3i1Obsv/lib/python3.7/site-packages/pykeen/models/unimodal/trans_h.py", line 134, in score_hrt
    d_r = self.relation_embeddings(hrt_batch[:, 1])
  File "/home/dobraczka/.local/share/virtualenvs/embedding-transformers-I3i1Obsv/lib/python3.7/site-packages/torch/nn/modules/module.py", line 550, in __call__
    result = self.forward(*input, **kwargs)
  File "/home/dobraczka/.local/share/virtualenvs/embedding-transformers-I3i1Obsv/lib/python3.7/site-packages/torch/nn/modules/sparse.py", line 114, in forward
    self.norm_type, self.scale_grad_by_freq, self.sparse)
  File "/home/dobraczka/.local/share/virtualenvs/embedding-transformers-I3i1Obsv/lib/python3.7/site-packages/torch/nn/functional.py", line 1724, in embedding
    return torch.embedding(weight, input, padding_idx, scale_grad_by_freq, sparse)
IndexError: index out of range in self
```
Loading e.g. the kinships dataset this way (i.e. concatenating train.txt, test.txt, valid.txt into a single file to have the same setting) I do not get this error. I have attached the data, which is a simple three-column tsv file.
[exampledata.txt](https://github.com/pykeen/pykeen/files/4953541/exampledata.txt)

**To Reproduce**
Steps to reproduce the behavior:
1. Execute the above script
2. See error

**Expected behavior**
Pipeline runs without errors and returns result.

**Environment (please complete the following information):**
 - OS: Debian Buster
 - Python version: 3.7
 - Version of this software: 1.0.2
 - Versions of required Python packages: 
click               7.1.2    
click-default-group 1.2.2    
numpy               1.19.0   
torch               1.5.1    
tqdm                4.48.0 


@dobraczka ~can you provide example data that causes this?~ My bad, I see you connected it! We had a similar issue that we were pretty sure was solved by https://github.com/pykeen/pykeen/pull/21

Update: I was able to confirm this error with a clean install of PyKEEN version 1.0.2