Check for 'detached' state and invalid branches passed

Add a check for if the tree is in a detached state, and also improve the
test on whether any references given as arguments to the constructor are
invalid with logging for all invalid refs not just the first detected.

Change-Id: Ieebc25337d842ee2cffddd03481da36877d2c27e

ghp/commands/import_upstream.py

@@ -41,26 +41,32 @@ class ImportUpstream(LogDedentMixin, GitMixin):
         # any computation
         super(ImportUpstream, self).__init__(*args, **kwargs)
 
+        # test that we can use this git repo
+        if not self.is_detached():
+            raise ImportUpstreamError("In 'detached HEAD' state")
+
         if self.repo.bare:
             raise ImportUpstreamError("Cannot perform imports in bare repos")
 
         if self.branch == 'HEAD':
             self._branch = self.repo.active_branch
 
-        branches = {
-            'upstream': self.upstream,
-            'branch': self.branch
-        }
+        # validate branches exist and log all failures
+        branches = [
+            self.branch,
+            self.upstream
+        ]
+        branches.extend(self.extra_branches)
 
-        if self._extra_branches != []:
-            branches.update({'extra branch %d' % idx: value
-                             for (idx, value) in enumerate(self.extra_branches, 1)})
-
-        for branch_type, branch in branches.iteritems():
+        invalid_ref = False
+        for branch in branches:
             if not any(head for head in self.repo.heads if head.name == branch):
-                msg = "Specified %s not found: '%s'"
-                self.log.error(msg, branch_type, branch)
-                raise ImportUpstreamError(msg % (branch_type, branch))
+                msg = "Specified ref does not exist: '%s'"
+                self.log.error(msg, branch)
+                invalid_ref = True
+
+        if invalid_ref:
+            raise ImportUpstreamError("Invalid ref")
 
     @property
     def branch(self):

ghp/lib/utils.py

@@ -31,3 +31,6 @@ class GitMixin(object):
     @property
     def git(self):
         return self.__git
+
+    def is_detached(self):
+        return self.git.symbolic_ref("HEAD", q=True, with_exceptions=False)