Going on a hunch

coursier.bzl

@@ -124,7 +124,7 @@ def _execute(repository_ctx, cmd, timeout = 600, environment = {}, progress_mess
 def _normalize_to_unix_path(path):
     if path == None:
         return None
-    return path.replace("\\\\", "/")
+    return path.replace("\\", "/")
 
 # Relativize an absolute path to an artifact in coursier's default cache location.
 # After relativizing, also symlink the path into the workspace's output base.
@@ -219,7 +219,7 @@ def _compute_dependency_tree_signature(artifacts):
         if artifact["file"] != None:
             artifact_group.extend([
                 artifact["sha256"],
-                artifact["file"],
+                artifact["file"].replace("\\", "/"),  # Make sure we represent files in a stable way cross-platform
                 artifact["url"],
             ])
         if len(artifact["dependencies"]) > 0:
@@ -930,8 +930,6 @@ def _coursier_fetch_impl(repository_ctx):
                 protocol = part
                 break
         if protocol == None:
-            # TODO: For debugging the builds
-            print(repr(dep_tree))
             fail("Only artifacts downloaded over http(s) are supported: %s - %s (analyzed %s)" % (artifact["coord"], artifact["file"], filepath_parts))
         primary_url_parts.extend([protocol, "://"])
         for part in filepath_parts[filepath_parts.index(protocol) + 1:]: