Use unix line-endings in bash activate script

Fixes: pypa#1818

Signed-off-by: Siddhant Kumar <skumar619@bloomberg.net>

src/virtualenv/activation/bash/__init__.py

@@ -1,13 +1,33 @@
 from __future__ import absolute_import, unicode_literals
 
+from virtualenv.info import IS_WIN
 from virtualenv.util.path import Path
 
 from ..via_template import ViaTemplateActivator
 
 
 class BashActivator(ViaTemplateActivator):
+    def generate(self, creator):
+        generated = super(BashActivator, self).generate(creator)
+        if IS_WIN:
+            _convert_to_unix_line_endings(generated)
+
     def templates(self):
         yield Path("activate.sh")
 
     def as_name(self, template):
         return template.stem
+
+
+def _convert_to_unix_line_endings(generated):
+    WINDOWS_LINE_ENDING = b"\r\n"
+    UNIX_LINE_ENDING = b"\n"
+
+    for file_path in generated:
+        with open(file_path, "rb") as open_file:
+            content = open_file.read()
+
+        content = content.replace(WINDOWS_LINE_ENDING, UNIX_LINE_ENDING)
+
+        with open(file_path, "wb") as open_file:
+            open_file.write(content)