_gitsourcebase.py: Strip git-describe tag info from cache key

The beginning parts of git-describe labels are completely arbitrary.
They can be changed either manually or by a track (e.g. if a tag is
moved, added or deleted) even if the referenced commit is the same.
Hence, only the commit ID part of the label should factor into the cache
key.

This commit, of course, breaks cache keys for artifacts built with the
'git' source with git-describe refs.

1 files changed, 7 insertions, 1 deletions

diff --git a/src/buildstream/_gitsourcebase.py b/src/buildstream/_gitsourcebase.py
index 7d1858a0a..271a08efc 100644
--- a/src/buildstream/_gitsourcebase.py
+++ b/src/buildstream/_gitsourcebase.py
@@ -530,10 +530,16 @@ class _GitSourceBase(Source):
         self.host_git = utils.get_host_tool("git")
 
     def get_unique_key(self):
+        ref = self.mirror.ref
+        if ref is not None:
+            # If the ref contains "-g" (is in git-describe format),
+            # only choose the part after, which is the commit ID
+            ref = ref.split("-g")[-1]
+
         # Here we want to encode the local name of the repository and
         # the ref, if the user changes the alias to fetch the same sources
         # from another location, it should not affect the cache key.
-        key = [self.original_url, self.mirror.ref]
+        key = [self.original_url, ref]
         if self.mirror.tags:
             tags = {tag: (commit, annotated) for tag, commit, annotated in self.mirror.tags}
             key.append({"tags": tags})