Filter files ending in '.repo' when searching for yum repos

yum internally only works with repos that reside in files ending
with '.repo'. This patch should make sure that Coriolis only looks
for repos inside files with filenames ending in '.repo'.

coriolis/osmorphing/redhat.py

@@ -217,14 +217,41 @@ class BaseRedHatMorphingTools(base.BaseLinuxOSMorphingTools):
             self._exec_cmd_chroot("rm -rf /var/cache/yum")
 
     def _find_yum_repos(self, repos_to_enable=[]):
+        """
+        Looks for required repositories passed as `repos_to_enable` in
+        /etc/yum.repos.d and returns the found repository names, so they can
+        be temporarily enabled when installing packages using yum.
+
+        Yum only looks for repos in files with '.repo' extension, anything
+        else gets ignored, therefore this method should filter files by that
+        extension.
+
+        Also, yum repository names might be different in some guest releases,
+        but still be similar. Therefore, repo name substrings should ideally be
+        passed in `repos_to_enable`. For example, we might be looking for repo
+        name 'ol7_latest', but the guest has it named as 'public_ol7_latest' in
+        the repo file.
+        """
         found_repos = []
+
+        reposdir_path = 'etc/yum.repos.d'
+
+        repofiles = [
+            f for f in self._list_dir(reposdir_path) if f.endswith('.repo')]
+        installed_repos = []
+        for file in repofiles:
+            path = os.path.join(reposdir_path, file)
+            content = self._read_file(path).decode()
+            for line in content.splitlines():
+                m = re.match(r'^\[(.+)\]$', line)
+                if m:
+                    installed_repos.append(m.group(1))
+
         for repo in repos_to_enable:
-            cmd = 'egrep "^\[.*%s.*\]$" -R /etc/yum.repos.d | cut -f2 -d:'
-            available_repos = self._exec_cmd_chroot(
-                cmd % repo).decode().splitlines()
+            available_repos = [ir for ir in installed_repos if repo in ir]
             available_repos.sort(key=len)
             if available_repos:
-                found_repos.append(available_repos[0].lstrip('[').rstrip(']'))
+                found_repos.append(available_repos[0])
             else:
                 LOG.warn(
                     "Could not find yum repository while searching for "