WDUK

Here's what you do!

1. Terminal: Unzip the ipa (it's just a zip file after all)
  unzip -q App.ipa
  
1a, You will need to have the entitlements file, this information is needed during signing.
  codesign -d --entitlements :- "Payload/App.app"
  
2. Terminal: This will produce a `Payload/` directory. Remove the existing code signature.
  rm -rf Payload/App.app/_CodeSignature

orta

post_install do |installer|
  app_plist = "Emergence/Info.plist"
  plist_buddy = "/usr/libexec/PlistBuddy"
  version = `#{plist_buddy} -c "Print CFBundleShortVersionString" #{app_plist}`.split
  puts "Updating CocoaPods' version numbers to #{version}"

  installer.pods_project.targets.each do |target|
    `#{plist_buddy} -c "Set CFBundleShortVersionString #{version}" "Pods/Target Support Files/#{target}/Info.plist"`
  end
end