Rebase the new bootstrap commits on the version repositories instead of

throwing away the old commits

README.md

@@ -85,9 +85,7 @@ Every now and then a new Clang subminor version is released. The given version c
 $GOPATH/src/github.com/go-clang/gen/scripts/update-clang-version.sh 3.4
 ```
 
-This will reset the commits of the `v3.4` repository to the latest commit of the `bootstrap` repository.  The command also generates, installs, configures and tests bindings for the given Clang version. The changes must then be manually verified, added, committed and pushed to the already set up remote "origin".
-
-> **Please note**, since we generate the whole binding anew we do not need the old commits and thus just throw them away.
+This will rebase the latest commits of the `bootstrap` repository onto the commits of the `v3.4` repository.  The command also generates, installs, configures and tests bindings for the given Clang version. The changes must then be manually verified, added, committed and pushed to the already set up remote "origin".
 
 ### Update branches with a new `go-clang/gen` version (VM)
 

scripts/update-clang-version.sh

@@ -1,24 +1,22 @@
 #!/bin/bash
 
+set -exuo pipefail
+
 if [ -z "$1" ]; then
 	exit
 fi
 
 export LLVM_VERSION=$1
 
 # Switch Clang version
-$(dirname "$0")/switch-clang-version.sh $LLVM_VERSION || exit
+$(dirname "$0")/switch-clang-version.sh $LLVM_VERSION
 
 # Update the repository
-cd v${LLVM_VERSION} || exit
+cd v${LLVM_VERSION}
 
-git checkout bootstrap/master || exit
-LAST_BOOTSTRAP=$(git rev-parse HEAD)
-git checkout master
-git reset --hard $LAST_BOOTSTRAP
+git fetch --prune bootstrap
 
-git fetch --prune bootstrap || exit
-git rebase bootstrap/master master
+git rebase master bootstrap/master
 
 # Generate the new Clang version
-$(dirname "$0")/generate-and-test.sh $LLVM_VERSION || exit
+$(dirname "$0")/generate-and-test.sh $LLVM_VERSION