Add fixes from PR review

* Drop python 3.4 from tox.ini
* Add Python 3.8 to tox.ini
* Correct variable names
* Change string to regex string

Author: caphrim007

hashin.py

@@ -392,13 +392,13 @@ def is_different_lines(old_lines, new_lines, indent):
         # in the lines being compared. This results in "old" names matching
         # "new" names so that hashin correctly replaces them when it looks for
         # them.
-        rex = re.compile("[-_]")
+        match_delims = re.compile(r"[-_]")
 
         # This assumes that the package is already mentioned in the old
         # requirements. Now we just need to double-check that its lines are
         # different.
         # The 'new_lines` is what we might intend to replace it with.
-        old = set([rex.sub("-", l.strip(" \\")) for l in old_lines])
+        old = set([match_delims.sub("-", line.strip(" \\")) for line in old_lines])
         new = set([indent + x.strip(" \\") for x in new_lines])
         return old != new
 

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py{27,34,35,36}, lint, restlint
+envlist = py{27,34,35,36,37}, lint, restlint
 
 [travis]
 python =