Add force-head script, which throws away everything and uses master

The script is intentionally not marked +x. The hasbang is just for
making clear that it's a shell script.

2 files changed, 26 insertions, 0 deletions

diff --git a/README.rst b/README.rst
index e713a1b..660e114 100644
--- a/README.rst
+++ b/README.rst
@@ -97,6 +97,21 @@ You can build a full mpv Debian package with the following command:
 The .deb file will be created in the parent directory. (4 is the number
 of jobs running in parallel - you can change it.)
 
+Forcing master versions of all parts
+====================================
+
+The following command can be used to delete all local changes, and to checkout
+the current master versions for all parts (libass, ffmpeg, mpv, as well as
+mpv-build itself):
+
+    sh ./force-head
+
+All local modifications are overwritten (including changes to the scripts),
+and git master versions are checked out. Breakages/bugs are to be expected,
+because these are untested bleeding-edge development versions of the code.
+
+Use on your own risk.
+
 Contact
 =======
 
diff --git a/force-head b/force-head
new file mode 100644
index 0000000..fa59004
--- /dev/null
+++ b/force-head
@@ -0,0 +1,11 @@
+#!/bin/sh
+
+update_master() {
+  git fetch && git checkout -f origin/master
+}
+
+update_master
+( cd libass && update_master ; )
+( cd ffmpeg && update_master ; )
+( cd mpv    && update_master ; )
+