Working request with Axios v1.0.0-alpha.1: 
```
axios.get('https://git.somegit.com/api/v3/search/commits?q=sort:committer-date-desc merge:false repo:org/reponame&per_page=50&page=1
```

Same request with 1.0.0 fails with a 404. 1.0.0 was promoted today. 

When I print the failed response it looks like something is parsed/encoded incorrectly. 

```
   request: <ref *1> ClientRequest {
      _events: [Object: null prototype],
      _eventsCount: 7,
       .....
       ..... 
      _headerSent: true,
      socket: [TLSSocket],
      _header: 'GET /api/v3/search/commitsq=sort%3Acommitter-date-desc+merge%3Afalse+repo%3Aorg%2Freponame&per_page=50&page=1 HTTP/1.1\r\n' +
        'Accept: application/vnd.github.cloak-preview+json;application/vnd.github.v3+json\r\n' +
        'User-Agent: axios/1.0.0\r\n' +
        'Accept-Encoding: gzip, deflate, br\r\n' +
        'Host: git.somegit.com\r\n' +
        'Connection: close\r\n' +
        '\r\n',

```
To me the `?` is missing in between `commits` and `q`. 

When I don't parse the parameters on the URL and use `config.params` it works with Axios `1.0.0`. 

```
    config.params = {
        q: `sort:committer-date-desc merge:false repo:org/reponame`,
        per_page: 50,
        page: 1
    }
```

The success response then shows this `_header`: 
```
 _header: 'GET /api/v3/search/commits?q=sort:committer-date-desc+merge:false+repo:org%2Freponame&per_page=50&page=1 HTTP/1.1\r\n' +
      'Accept: application/vnd.github.cloak-preview+json;application/vnd.github.v3+json\r\n' +
      'User-Agent: axios/1.0.0\r\n' +
      'Accept-Encoding: gzip, deflate, br\r\n' +
      'Host: git.somegit.com\r\n' +
      'Connection: close\r\n' +
      '\r\n',

```
In the working version I do see the `?`. 

So right now the workaround is either sticking with v1.0.0-alpha.1 or using config.params instead of passing them with the .get call. 


lib/adapters/http.js
if (proxy.username) {
      proxy.auth = (proxy.username || '') + ':' + (proxy.password || '');
    }
    if (proxy.auth) {
      
      if (proxy.auth.username || proxy.auth.password) {
        proxy.auth = (proxy.auth.username || '') + ':' + (proxy.auth.password || '');
      }
      const base64 = Buffer
        .from(proxy.auth, 'utf8')
        .toString('base64');
      options.headers['Proxy-Authorization'] = 'Basic ' + base64;
    }
    options.headers.host = options.hostname + (options.port ? ':' + options.port : '');
    options.hostname = proxy.hostname;
    
    options.host = proxy.hostname;
    options.port = proxy.port;
    options.path = location;
    if (proxy.protocol) {
      options.protocol = proxy.protocol;
    }
  }
  options.beforeRedirects.proxy = function beforeRedirect(redirectOptions) {
    
    
    setProxy(redirectOptions, configProxy, redirectOptions.href);
  };
}
export default function httpAdapter(config) {