FULL PRODUCT VERSION :


ADDITIONAL OS VERSION INFORMATION :
Windows 7 Enterprise SP1 x86

A DESCRIPTION OF THE PROBLEM :
This could have the same root cause as "JDK-8062034 : Java not utilising PAC or WPAD", but since the symptoms are not strictly identical I post mine here for the records:

1. IE is setup to use a configuration script that use a PROXY unless the requested hostname is on the intranet (in that case DIRECT should be used)
2. Browse a website on the intranet
3. The java plugin fails to download the jar
4. If we manually type the jar URL in IE, it downloads just fine

As a workaround we could change the Java network settings to use "Direct connection" (this is not really easy to use since we must switch the config each time we switch from intranet/internet)

REGRESSION.  Last worked in version 7u67

ADDITIONAL REGRESSION INFORMATION: 
Right now I have 1.7.0_72:
D:\>java -version
java version "1.7.0_72"
Java(TM) SE Runtime Environment (build 1.7.0_72-b14)
Java HotSpot(TM) Client VM (build 24.72-b04, mixed mode, sharing)

and it fails at that version, but it also fails with the 1.7.0_71


REPRODUCIBILITY :
This bug can be reproduced always.