Please describe the problem:
This bug is similar to bug #312322 - but it does not cause some parts of documentation to be missing, it causes errors with \cond and \endcond clauses. If those commands exists between odd and even occurences of apostrophes in Python comments they are not handled properly. 

Steps to reproduce:
Try to document file with following contents:

# This comment contains unpaired apostrophe: ' 

## Some namespace
# \namespace doxbug

## \cond DEVEL

## Brief description of DEVEL_func1
# This function is NOT documented properly, but as if "cond" command does 
# not exist.
def DEVEL_func1():
    pass

## \endcond

## Brief description of func2
# This function is documented properly
def func2():
    pass

# comment with second ', "closing" the pair
    
## \cond DEVEL

## Brief description of DEVEL_func3
# This function is documented properly
def DEVEL_func3():
    pass

## \endcond


Actual results:
Following errors can be seen in doxygen output:

Generating docs for namespace doxbug
D:/doxygen/doxbug.py:8: Warning: Found unknown command `\cond'
D:/doxygen/doxbug.py:15: Warning: Found unknown command `\endcond'
D:/doxygen/doxbug.py:8: Warning: Found unknown command `\cond'
D:/doxygen/doxbug.py:15: Warning: Found unknown command `\endcond'

DEVEL_func1 is included in the docs although ENABLED_SECTIONS configuration variable does not contain DEVEL section.

Expected results:
\cond and \endcond commands are recognized properly.

Does this happen every time?
Yes.

Other information:
It may be possible that this bug also applies to other commands but I'm unable to check that now.