Merge pull request #756 from bower/meaningful-proxy-error

Add additional message for proxy users about https//.insteadOf git://, fixes #250.

lib/core/resolvers/GitRemoteResolver.js

@@ -72,12 +72,29 @@ GitRemoteResolver.prototype._checkout = function () {
     }, 8000);
 
     return promise
+    // Add additional proxy information to the error if necessary
+    .fail(function (err) {
+        that._suggestProxyWorkaround(err);
+        throw err;
+    })
     // Clear timer at the end
     .fin(function () {
         clearTimeout(timer);
     });
 };
 
+GitRemoteResolver.prototype._findResolution = function (target) {
+    var that = this;
+
+    // Override this function to include a meaningful message related to proxies
+    // if necessary
+    return GitResolver.prototype._findResolution.call(this, target)
+    .fail(function (err) {
+        that._suggestProxyWorkaround(err);
+        throw err;
+    });
+};
+
 // ------------------------------
 
 GitRemoteResolver.prototype._slowClone = function (resolution) {
@@ -124,10 +141,21 @@ GitRemoteResolver.prototype._fastClone = function (resolution) {
     });
 };
 
-// ------------------------------
+GitRemoteResolver.prototype._suggestProxyWorkaround = function (err) {
+    if ((this._config.proxy || this._config.httpsProxy) &&
+        mout.string.startsWith(this._source, 'git://') &&
+        err.code === 'ECMDERR' && err.details
+    ) {
+        err.details = err.details.trim();
+        err.details += '\n\nWhen under a proxy, you must configure git to use https:// instead of git://.';
+        err.details += '\nYou can configure it for every endpoint or for this specific host as follows:';
+        err.details += '\ngit config --global url."https://".insteadOf git://';
+        err.details += '\ngit config --global url."https://' + this._host + '".insteadOf git://' + this._host;
+        err.details += 'Ignore this suggestion if you already have this configured.';
+    }
+};
 
-// Store hosts that do not support shallow clones here
-GitRemoteResolver._noShallow = new LRU({ max: 50, maxAge: 5 * 60 * 1000 });
+// ------------------------------
 
 // Grab refs remotely
 GitRemoteResolver.refs = function (source) {
@@ -162,4 +190,7 @@ GitRemoteResolver.refs = function (source) {
     return value;
 };
 
+// Store hosts that do not support shallow clones here
+GitRemoteResolver._noShallow = new LRU({ max: 50, maxAge: 5 * 60 * 1000 });
+
 module.exports = GitRemoteResolver;