Disable progress bar on CI.

Author: ehuss

src/cargo/util/progress.rs

@@ -38,11 +38,13 @@ struct Format {
 impl<'cfg> Progress<'cfg> {
     pub fn with_style(name: &str, style: ProgressStyle, cfg: &'cfg Config) -> Progress<'cfg> {
         // report no progress when -q (for quiet) or TERM=dumb are set
+        // or if running on Continuous Integration service like Travis where the
+        // output logs get mangled.
         let dumb = match env::var("TERM") {
             Ok(term) => term == "dumb",
             Err(_) => false,
         };
-        if cfg.shell().verbosity() == Verbosity::Quiet || dumb {
+        if cfg.shell().verbosity() == Verbosity::Quiet || dumb || env::var("CI").is_ok() {
             return Progress { state: None };
         }