Reland of Teach bot_update to support patching deps in solutions other than the patch_root

scripts/slave/bot_update.py

Index: scripts/slave/bot_update.py
diff --git a/scripts/slave/bot_update.py b/scripts/slave/bot_update.py
index 51c79eba4ce9155bb6dbc12ff1670aadfb3ed40b..b066044d9a897635c52f1e8858635c5c5f2bc7b2 100755
--- a/scripts/slave/bot_update.py
+++ b/scripts/slave/bot_update.py
@@ -1257,15 +1257,20 @@ def ensure_checkout(solutions, revisions, first_sln, target_os, target_os_only,
   if patch_url:
     patches = get_svn_patch(patch_url)
 
+  already_patched = []
+  patch_root = patch_root or ''
   for solution in solutions:
-    # At first, only patch top-level DEPS.
-    if patch_root == solution['name']:
+    if (patch_root == solution['name'] or
+        solution['name'].startswith(patch_root + '/')):
+      relative_root = solution['name'][len(patch_root) + 1:]
+      target = '/'.join([relative_root, 'DEPS']).lstrip('/')
       if patches:
-        apply_svn_patch(patch_root, patches, whitelist=['DEPS'])
+        apply_svn_patch(patch_root, patches, whitelist=[target])
+        already_patched.append(target)
       elif issue:
         apply_rietveld_issue(issue, patchset, patch_root, rietveld_server,
-                            revision_mapping, git_ref, whitelist=['DEPS'])
-      break
+                            revision_mapping, git_ref, whitelist=[target])
+        already_patched.append(target)
 
   if buildspec:
     buildspecs2git(first_sln, buildspec)
@@ -1298,10 +1303,10 @@ def ensure_checkout(solutions, revisions, first_sln, target_os, target_os_only,
                         dir_names, revisions)
   # Apply the rest of the patch here (sans DEPS)
   if patches:
-    apply_svn_patch(patch_root, patches, blacklist=['DEPS'])
+    apply_svn_patch(patch_root, patches, blacklist=already_patched)
   elif issue:
     apply_rietveld_issue(issue, patchset, patch_root, rietveld_server,
-                         revision_mapping, git_ref, blacklist=['DEPS'])
+                         revision_mapping, git_ref, blacklist=already_patched)
 
   # Reset the deps_file point in the solutions so that hooks get run properly.
   for sln in solutions: