Merge ~racb/usd-importer:lp/1661092 into usd-importer:master

[Robie Basak]

[Nish Aravamudan (nacc)]

review: Approve

diff --git a/usd/build.py b/usd/build.py
index dc689e1..69574f7 100644
--- a/usd/build.py
+++ b/usd/build.py
@@ -211,7 +211,9 @@ class USDBuild:
                                     pkgname, distname)
 
         if not upstream_version_found:
-            raise NoUpstreamFoundException
+            raise NoUpstreamFoundException("Unable to find any prior "
+                                           "publish with a matching upstream "
+                                           "version to %s" % changelog.full_version)
 
         # symlink orig tarballs
         for entry in dsc['Files']:
diff --git a/usd/git_repository.py b/usd/git_repository.py
index 93aa853..3132c44 100644
--- a/usd/git_repository.py
+++ b/usd/git_repository.py
@@ -247,7 +247,7 @@ class USDGitRepository:
             # Does not seem to be working with https
             # self.local_repo.remotes[remote_name].fetch()
             self.git_run(['fetch', remote_name])
-        except:
+        except CalledProcessError:
             logging.info('No objects found in remote %s', remote_url)
 
         self.local_repo.remotes.set_push_url(remote_name,
@@ -367,16 +367,28 @@ class USDGitRepository:
         else:
             raise Exception('Unknown changelog field %s' % field)
 
+        # We cannot use "git show" since it does not follow symlinks (LP:
+        # #1661092). Instead, use "git cat-file --batch --follow-symlinks" and
+        # parse the batch output (first line) to ensure that we get a blob
+        # rather than a symlink following failure. If we don't get a blob, then
+        # print what we got and exit 1.
+        cat_changelog_cmd = (
+            "echo %s:debian/changelog | "
+            "git cat-file --batch --follow-symlinks | "
+            "sed -n '1{/^[^ ]* blob/!{p;q1}};2,$p'"
+            % treeish
+        )
+
         try:
             cp = run(
-                'git show %s:debian/changelog | dpkg-parsechangelog -l- %s' %
-                (treeish, parse_params),
+                '%s | dpkg-parsechangelog -l- %s' %
+                (cat_changelog_cmd, parse_params),
                 shell=True, env=self._env)
         except CalledProcessError:
             try:
-                cp = run('git show %s:debian/changelog | %s' % (treeish,
-                                                                shell_cmd),
-                         shell=True, env=self._env)
+                cp = run(
+                    '%s | %s' % (cat_changelog_cmd, shell_cmd),
+                    shell=True, env=self._env)
             except CalledProcessError:
                 raise Exception('Unable to parse changelog')
 
diff --git a/usd/importer.py b/usd/importer.py
index 73de6a6..594b271 100755
--- a/usd/importer.py
+++ b/usd/importer.py
@@ -374,7 +374,8 @@ class USDImport:
                 break
         if extracted_dir is None:
             logging.exception('No source extracted?')
-            raise SourceExtractionException
+            raise SourceExtractionException("Failed to find an extracted "
+                                            "directory from dpkg-source -x")
 
         self.local_repo.git_run(['--work-tree', extracted_dir, 'add', '-f', '-A'])
         cp = self.local_repo.git_run(['--work-tree', extracted_dir, 'write-tree'])
@@ -411,7 +412,8 @@ class USDImport:
                 break
         if extracted_dir is None:
             logging.exception('No source extracted?')
-            raise SourceExtractionException
+            raise SourceExtractionException("Failed to find an extracted "
+                                            "directory from dpkg-source -x")
 
         if os.path.isdir(os.path.join(extracted_dir, '.pc')):
             self.local_repo.git_run(['--work-tree', extracted_dir, 'add', '-f', '-A'])
@@ -425,7 +427,7 @@ class USDImport:
                 cp = run(['dpkg-source', '--print-format', extracted_dir])
                 fmt = decode_binary(cp.stdout).strip()
                 if '3.0 (quilt)' not in fmt:
-                    raise StopIteration
+                    raise StopIteration()
             except CalledProcessError as e:
                 try:
                     with open('debian/source/format', 'r') as f:
@@ -433,10 +435,10 @@ class USDImport:
                              if re.match(r'3.0 (.*)', line):
                                  break
                         else:
-                             raise StopIteration
+                             raise StopIteration()
                 # `man dpkg-source` indicates no d/s/format implies 1.0
                 except OSError:
-                    raise StopIteration
+                    raise StopIteration()
 
             while True:
                 try:
@@ -467,7 +469,7 @@ class USDImport:
                     # quilt returns 2 when done pushing
                     if e.returncode != 2:
                         raise
-                    raise StopIteration
+                    raise StopIteration()
         finally:
             os.chdir(oldcwd)
             shutil.rmtree(extract_dir)
diff --git a/usd/source_information.py b/usd/source_information.py
index c6a74be..f766ddf 100644
--- a/usd/source_information.py
+++ b/usd/source_information.py
@@ -197,6 +197,7 @@ class USDSourceInformation(object):
                  retry_backoffs
                 ):
         self.launchpad = launchpad_login()
+        self.dist_name = dist_name
         self.dist = self.launchpad.distributions[dist_name]
         self.pkgname = pkgname
         self.parse_pullfile(pull_overrides_filename)
@@ -249,7 +250,8 @@ class USDSourceInformation(object):
 
         spph = self.dist.main_archive.getPublishedSources(**args)
         if len(spph) == 0:
-            raise NoPublicationHistoryException
+            raise NoPublicationHistoryException("Is %s published in %s?" %
+                                                (self.pkgname, self.dist_name))
 
         for srcpkg in spph:
             yield self.get_corrected_spi(srcpkg, workdir)
@@ -280,7 +282,8 @@ class USDSourceInformation(object):
         # Sanity check that the passed in srcpkg name has a publication
         # history
         if len(spph) == 0:
-            raise NoPublicationHistoryException
+            raise NoPublicationHistoryException("Is %s published in %s?" %
+                                                (self.pkgname, self.dist_name))
         if len(head_versions) > 0:
             _spph = list()
             for spphr in spph:
@@ -311,7 +314,7 @@ class USDSourceInformation(object):
                 )
                )
             yield self.get_corrected_spi(srcpkg, workdir)
-        raise StopIteration
+        raise StopIteration()
 
     def parse_pullfile(self, pullfile):
         """Extract source file overrides from a file