build.sh: Enable to specify a custom branch from the dev repo

There are multiple reasons why the branch might not be called main:
- It could be called master
- We might want to test a specific feature branch
- When using GitLab or GitHub to test merge requests
etc.

Signed-off-by: Sebastian Fricke <sebastian.fricke@collabora.com>

build.sh

@@ -189,7 +189,7 @@ if [ "$1" == "setup" ]; then
 	cd ..
 
 	cd media-git
-	git remote add main $myrepo
+	git remote add $mybranch $myrepo
 	if [ -n "$mylocalrepo" ]; then
 		git remote add local $mylocalrepo
 	fi

env.tmpl

@@ -5,6 +5,8 @@
 # Your main git tree where you keep your in-progress work.
 # This will be named 'main'.
 myrepo=git://linuxtv.org/hverkuil/media_tree.git
+# You can also specify a specific branch to checkout
+#mybranch=example_branch
 
 # Optional: your local git tree where you do your development
 # This will be named 'local', so to build a branch from your