shellpattern: add match_end arg

match_end=r"\Z" is the default, same behaviour as before
(create a full match up to the string end from the globbing pattern).

match_end=otherregex can be flexibly used to match anything else
after the regex generated from the globbing pattern.

src/borg/shellpattern.py

@@ -2,7 +2,7 @@ import os
 import re
 
 
-def translate(pat):
+def translate(pat, match_end=r"\Z"):
     """Translate a shell-style pattern to a regular expression.
 
     The pattern may include ``**<sep>`` (<sep> stands for the platform-specific path separator; "/" on POSIX systems) for
@@ -10,6 +10,9 @@ def translate(pat):
     any path separator. Wrap meta-characters in brackets for a literal match (i.e. "[?]" to match the literal character
     "?").
 
+    Using match_end=regex one can give a regular expression that is used to match after the regex that is generated from
+    the pattern. The default is to match the end of the string.
+
     This function is derived from the "fnmatch" module distributed with the Python standard library.
 
     Copyright (C) 2001-2017 Python Software Foundation. All rights reserved.
@@ -59,4 +62,4 @@ def translate(pat):
         else:
             res += re.escape(c)
 
-    return res + r"\Z(?ms)"
+    return res + match_end + "(?ms)"

src/borg/testsuite/shellpattern.py

@@ -111,3 +111,14 @@ def test_match(path, patterns):
 def test_mismatch(path, patterns):
     for p in patterns:
         assert not check(path, p)
+
+
+def test_match_end():
+    regex = shellpattern.translate("*-home")  # default is match_end == string end
+    assert re.match(regex, '2017-07-03-home')
+    assert not re.match(regex, '2017-07-03-home.checkpoint')
+
+    match_end = r'(%s)?\Z' % r'\.checkpoint(\.\d+)?'  # with/without checkpoint ending
+    regex = shellpattern.translate("*-home", match_end=match_end)
+    assert re.match(regex, '2017-07-03-home')
+    assert re.match(regex, '2017-07-03-home.checkpoint')