no branch info available yet in scmdiff, so disable for now

Dependencies

• [2] TH674WKJ add log diff to compare logs to previous builds
• [3] BKOIYITR added some json responses
• [4] SHYRGAWZ hydra: when no external url is given for diff's of git/hg input, revert to a diff done on a local available clone

Change contents

• replacement in src/lib/Hydra/Controller/API.pm at line 218
  [3.552]→[2.84:151](∅→∅)
  − $diff .= `(cd $clonePath ; hg log -r $rev1 -r $rev2 -b $branch)`;
  [3.552]

  [3.605]
  + $diff .= `(cd $clonePath ; hg log -r $rev1 -r $rev2)`;