Improve specificity further.

The non-zero-padded template must not start with `0` in the image number,
so add that to the template. Then there are 4 groups, so add a condition
to handle this case separately.

src/dxtbx/model/scan_helpers.py

@@ -14,7 +14,7 @@
     r"([0-9]{2,12})\.(.*)",
     r"(.*)\.([0-9]{2,12})_(.*)",
     r"(.*)\.([0-9]{2,12})(.*)",
-    r"(.*)\.([0-9]{1,12})_(.*)",
+    r"(.*)\.([0-9]{1,12})([^0]*)_(.*)",
     r"(.*)\.([0-9]{1})(.*)",
 ]
 
@@ -39,6 +39,10 @@ def template_regex(filename):
             exten = "." + groups[0][::-1]
             digits = groups[1][::-1]
             prefix = groups[2][::-1] + joiners[j]
+        elif len(groups) == 4:
+            exten = "." + groups[0][::-1]
+            digits = groups[1][::-1]
+            prefix = groups[3][::-1] + joiners[j] + groups[2][::-1]
         else:
             exten = ""
             digits = groups[0][::-1]