* apt-pkg/contrib/configuration.cc:

  - fix double delete (LP: #848907)
  - ignore only the invalid regexp instead of all options
* apt-pkg/acquire-item.h, apt-pkg/deb/debmetaindex.cc:
  - fix fetching language information by adding OptionalSubIndexTarget
* methods/https.cc:
  - cleanup broken downloads properly

* ftparchive/cachedb.cc:
  - fix buffersize in bytes2hex
* apt-pkg/deb/deblistparser.cc:
  - fix crash when the dynamic mmap needs to be grown in
    LoadReleaseInfo (LP: #854090)