[meld] dirdiff: Fix folder comparison ignore blank lines with filters (#314)

[Kai Willadsen <kaiw src gnome org>]

commit 7770fea79af79a0bb6fc357f88271449cf377dfe
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Mon May 6 08:49:55 2019 +1000

    dirdiff: Fix folder comparison ignore blank lines with filters (#314)
    
    Because of the order of operations, folder comparisons weren't ignoring
    blank line differences when the blank lines were the result of applying
    text filters.

 meld/dirdiff.py | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/meld/dirdiff.py b/meld/dirdiff.py
index a73dd727..4b41e125 100644
--- a/meld/dirdiff.py
+++ b/meld/dirdiff.py
@@ -141,6 +141,10 @@ def _normalize(contents, ignore_blank_lines, regexes=()):
 
     if regexes:
         contents = (apply_text_filters(c, regexes) for c in contents)
+        if ignore_blank_lines:
+            # We re-remove blank lines here in case applying text
+            # filters has caused more lines to be blank.
+            contents = (remove_blank_lines(c) for c in contents)
 
     return contents