Android branches

List all branches in an Android:
git --git-dir .repo/manifests/.git/ branch -a

Checking out the 2.3.6..
git --git-dir .repo/manifests/.git/ checkout android-2.3.6_r1

To update cacerts.bk on the emulator, make sure you set the partition-size.  Otherwise, you may see "Out of Memory" exceptions:

~/projects/android/android-sdk-linux/tools/emulator-arm -avd <.avd image> -partition-size 128

Then you can pull the cert

./adb pull /system/etc/security/cacerts.bks android23_cacerts.bks  

To use keytool to add a cert, you need to install the BouncyCastleProvider (bcprov-jdk16-146.jar) into /usr/lib/jvm/java-6-openjdk/jre/lib/ext dir.

keytool -keystore android22_cacerts.bks -storetype BKS -provider org.bouncycastle.jce.provider.BouncyCastleProvider -storepass changeit -import -v -file bla.cer

./adb shell mount -o remount, rw /system

/adb push android22_cacerts.bks /system/etc/security/cacerts.bks