Py2 doesn't like using unmatched groups in regex results

1 files changed, 1 insertions, 1 deletions

diff --git a/coverage/misc.py b/coverage/misc.py
index c6a7c8cf..037332f5 100644
--- a/coverage/misc.py
+++ b/coverage/misc.py
@@ -271,7 +271,7 @@ def substitute_variables(text, variables=os.environ):
     def dollar_replace(m):
         """Called for each $replacement."""
         # Only one of the groups will have matched, just get its text.
-        word = m.expand(r"\g<v1>\g<v2>\g<char>")
+        word = ''.join(m.group(name) or '' for name in ['v1', 'v2', 'char'])
         if word == "$":
             return "$"
         else: