[PATCH v2] Create from local branch before applying patches with git

[Jan Kiszka <jan.kiszka@siemens.com>]

From: Jan Kiszka <jan.kiszka@siemens.com>

If refspec is pointing to an upstream branch name, the checkout for a
second run will not reset a repo back to the upstream commit. That is
because we applied the repo patches to a local branch that carries the
name of the upstream one.

Fix that by switching to local branch prior to applying any patches.

Reported-by: Belisko Marek <marek.belisko@gmail.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

Changes in v2:
 - rebased over next
 - add hg support
 - use local branch also with git

 kas/repos.py | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/kas/repos.py b/kas/repos.py
index 4f74f4b..113a67f 100644
--- a/kas/repos.py
+++ b/kas/repos.py
@@ -247,9 +247,14 @@ class RepoImpl(Repo):
         """
             Applies patches to a repository asynchronously.
         """
-        if self.operations_disabled:
+        if self.operations_disabled or not self._patches:
             return 0
 
+        (retc, _) = yield from run_cmd_async(self.prepare_patches_cmd(),
+                                             cwd=self.path)
+        if retc:
+            return retc
+
         my_patches = []
 
         for patch in self._patches:
@@ -359,6 +364,9 @@ class GitRepo(RepoImpl):
         return ['git', 'checkout', '-q',
                 '{refspec}'.format(refspec=self.refspec)]
 
+    def prepare_patches_cmd(self):
+        return ['git', 'checkout', '-q', '-B', 'local-kas-patches']
+
     def apply_patches_file_cmd(self, path):
         return ['git', 'apply', path]
 
@@ -395,6 +403,9 @@ class MercurialRepo(RepoImpl):
     def checkout_cmd(self):
         return ['hg', 'checkout', '{refspec}'.format(refspec=self.refspec)]
 
+    def prepare_patches_cmd(self):
+        return ['hg', 'branch', '-f', 'local-kas-patches']
+
     def apply_patches_file_cmd(self, path):
         return ['hg', 'import', '--no-commit', path]
 
-- 
2.16.4


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