style: wrap multiline strings elegantly

borg/cache.py

@@ -74,7 +74,8 @@ class Cache:
         self.close()
 
     def __str__(self):
-        return format(self, """All archives:   {0.total_size:>20s} {0.total_csize:>20s} {0.unique_csize:>20s}
+        return format(self, """\
+All archives:   {0.total_size:>20s} {0.total_csize:>20s} {0.unique_csize:>20s}
 
                        Unique chunks         Total chunks
 Chunk index:    {0.total_unique_chunks:20d} {0.total_chunks:20d}""")

borg/helpers.py

@@ -148,7 +148,8 @@ class Statistics:
         return buf
 
     def __str__(self):
-        return format(self, """                       Original size      Compressed size    Deduplicated size
+        return format(self, """\
+                       Original size      Compressed size    Deduplicated size
 %-15s {0.osize:>20s} {0.csize:>20s} {0.usize:>20s}""")
 
     def __format__(self, format_spec):