[BUG] more travis issues. Unknown what the cause it
error message:

```
Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection object at 0x7f286ebec8d0>: Failed to establish a new connection: [Errno -2] Name or service not known')': /simple/mpi4py/
```

seem by @coquelin77 and @simon-schmitz 
diff --git a/.travis.yml b/.travis.yml
index 8d4149a4..3d1d2b3e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -12,6 +12,7 @@ before_install:
 
 install:
   - docker exec -t unittest /bin/bash -c '. /root/.bashrc && pip install -q -e .[hdf5,netcdf]'
+  - pip list
  
 script:
   # Running multiple mpi process count, generate a unique coverage report for each one and merge into one report
diff --git a/heat/core/linalg.py b/heat/core/linalg.py
index b93d7185..2eb26bd1 100644
--- a/heat/core/linalg.py
+++ b/heat/core/linalg.py
@@ -63,7 +63,7 @@ def transpose(a, axes=None):
 
         return dndarray.DNDarray(transposed_data, transposed_shape, a.dtype, transposed_split, a.device, a.comm)
     # if not possible re- raise any torch exception as ValueError
-    except RuntimeError as exception:
+    except (RuntimeError, IndexError) as exception: 
         raise ValueError(str(exception))
 
 
['.travis.yml', 'heat/core/linalg.py']