(PDB-126) Command retries should log the exception's stacktrace

Current code was only logging the exception message to the log
(not the stacktrace).
Merge pull request #778 from senior/ticket/1.5.x/pdb-126-command-retry-stacktraces

(PDB-126) Command retries should log the exception's stacktrace
Merge branch '1.5.x'

* 1.5.x:
  (PDB-126) Command retries should log the exception's stacktrace