Output of invalid indents when comments appear inside implicit string continuations

A comment inside a string breaks the tools as it unnecessarily appends line continuations to strings

i.e. this chokes

foo('a'
    # foo
    'b')

A real example

-            self.assertEqual('\n' + STR_PROJECT_WIDE + '\n\n'
-                             '**** t [Section: ] ****' + '\n\n'
-                             '!    ! [Severity: NORMAL]\n'
-                             '!    ! msg\n'
-                             # Second results file isn't there, no context is
-                             # printed, only a warning log message which we
-                             # don't catch
-                             '\n**** t [Section: ] ****' + '\n\n'
-                             '!    ! [Severity: NORMAL]\n'
+            assert '\n' + STR_PROJECT_WIDE + '\n\n' \
+                             '**** t [Section: ] ****' + '\n\n' \
+                             '!    ! [Severity: NORMAL]\n' \
+                             '!    ! msg\n' \
+                             # Second results file isn't there, no context is \
+                             # printed, only a warning log message which we \
+                             # don't catch \
+                             '\n**** t [Section: ] ****' + '\n\n' \
+                             '!    ! [Severity: NORMAL]\n' \
                              '!    ! {0}\n'.format(
                                  highlight_text(self.no_color, 'msg',
-                                                style=BackgroundMessageStyle)),
-                             stdout.getvalue())
+                                                style=BackgroundMessageStyle)) == \
+                             stdout.getvalue()

From https://github.com/coala/coala/blob/8a25983/tests/output/ConsoleInteractionTest.py#L623

Result: https://travis-ci.org/jayvdb/coala/jobs/246949584#L9052

(Another bug coming about the other problem in that build log.)

Start by reproducing the issue with the implicit string continuation example and trace how unittest2pytest handles comments between adjacent string literals. The referenced tests/output/ConsoleInteractionTest.py example shows the unwanted backslashes; done means comments remain valid and the converted output no longer appends line continuations unnecessarily.