Use try..finally blocks to ensure calls within context manager

bin/backup

@@ -108,9 +108,11 @@ def change_umask():
     """Creates a context manager in which the umask is changed. This is to ensure that
     the script's desired umask is not visible to the user.
     """
-    old_umask = os.umask(SCRIPT_UMASK)
-    yield
-    os.umask(old_umask)
+    try:
+        old_umask = os.umask(SCRIPT_UMASK)
+        yield
+    finally:
+        os.umask(old_umask)
 
 
 # ========== Main Script ==========

rbackup/config.py

@@ -95,9 +95,12 @@ def merge_include_files():
 
     :return: path-like object
     """
-    filelist = merge_files(get_files_by_suffix("-include.conf"))
-    yield filelist
-    filelist.unlink()
+    try:
+        # filelist is guaranteed to exist at this point
+        filelist = merge_files(get_files_by_suffix("-include.conf"))
+        yield filelist
+    finally:
+        filelist.unlink()
 
 
 @contextmanager
@@ -106,9 +109,12 @@ def merge_exclude_files():
 
     :return: path-like object
     """
-    filelist = merge_files(get_files_by_suffix("-exclude.conf"))
-    yield filelist
-    filelist.unlink()
+    try:
+        # filelist is guaranteed to exist at this point
+        filelist = merge_files(get_files_by_suffix("-exclude.conf"))
+        yield filelist
+    finally:
+        filelist.unlink()
 
 
 def parse_configfile():