Remove colon from image caption if there is no actualf caption text

src/imxml2epub.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8; mode: python -*-
-# Time-stamp: <2020-09-02 09:13:11 (kthoden)>
+# Time-stamp: <2020-09-24 16:09:29 (kthoden)>
 
 """ Convert a customized DocBook XML file into a set of files that
 constitute the contents of an EPUB file.
@@ -830,7 +830,10 @@ def add_css_snippet(css_snippet, css_file):
     dictLangFigures = translation_xml.find("//entry[@name='fig']").attrib
     xmlChapter = xmlFigure.xpath("./ancestor::div1")[0]
     figures_text = dictLangFigures[libeoaconvert.two_letter_language(xmlChapter.get("language"))]
-    xmlFigureCaption.text = f"{figures_text} {str(intFigureNumber)}: {strFigureCaption}"
+    if len(strFigureCaption) == 0:
+        xmlFigureCaption.text = f"{figures_text} {str(intFigureNumber)}"
+    else:
+        xmlFigureCaption.text = f"{figures_text} {str(intFigureNumber)}: {strFigureCaption}"
     xmlFigure.addnext(xmlFigureCaption)
     # Change the tag of the parent <p>-Tag to <div> so that it may be removed
     #xmlFigure.getparent().tag = "div"