* src/LaTeXFeatures.cpp:

- handle case where natbib is loaded internally by a class, but still plain cite commands
	  have to be output (bug 5182)
* lib/revtex4.layout:
	- this is such a case.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@26298 a592a061-630c-0410-9148-cb99ea01b6c8

lib/layouts/revtex4.layout

@@ -14,7 +14,7 @@ Format 8
 Columns                 1
 Sides                   1
 PageStyle               Headers
-Provides natbib		1
+Provides natbib-internal	1
 Provides url		1
 
 # Default textclass options. The user may need to modify this.

src/LaTeXFeatures.cpp

@@ -599,7 +599,11 @@ string const LaTeXFeatures::getPackages() const
 		packages << "\\usepackage{esint}\n";
 
 	// natbib.sty
-	if (mustProvide("natbib")) {
+	// Some classes load natbib themselves, but still allow (or even require)
+	// plain numeric citations (ReVTeX is such a case, see bug 5182).
+	// This special case is indicated by the "natbib-internal" key.
+	if (mustProvide("natbib")
+	    && !params_.getTextClass().provides("natbib-internal")) {
 		packages << "\\usepackage[";
 		if (params_.citeEngine() == ENGINE_NATBIB_NUMERICAL)
 			packages << "numbers";