** Description changed:

  [Impact]
  
  when authenticate AD, with bask-completion, it's very slow.
  
  [Testcase]
  
  Below command should output nothing.
  
  root@ubuntu1404:~# strace bash -c ". /etc/bash_completion; quote_readline 
'/something'; echo" 2>&1 | grep /etc/passwd
  root@ubuntu1404:~# strace bash -c ". /etc/bash_completion; quote_readline 
'/something'; echo" 2>&1 | grep sss
  
  but we have something
  
  root@ubuntu1404:~# strace bash -c ". /etc/bash_completion; quote_readline 
'/something'; echo" 2>&1 | grep /etc/passwd
  open("/etc/passwd", O_RDONLY|O_CLOEXEC) = 3
  root@ubuntu1404:~# strace bash -c ". /etc/bash_completion; quote_readline 
'/something'; echo" 2>&1 | grep sss
  open("/lib/i386-linux-gnu/libnss_sss.so.2", O_RDONLY|O_CLOEXEC) = 3
  open("/var/lib/sss/mc/passwd", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = 3
  connect(4, {sa_family=AF_LOCAL, sun_path="/var/lib/sss/pipes/nss"}, 110) = 0
  
  [Regeression Potential]
+ 
+ Regression possible about
+ https://bugs.launchpad.net/ubuntu/+source/bash/+bug/1288314
+ 
+ but there is no problem with ~ completion in my test
+ 
+ I thested ~/<Tab>/ ~/<Tab>/<Tab> with no problem
  
  [Other Info]
  
  This is not from upstream, no need to fix for upstream.
  But fix code seems harmless. just specify special character ~
  
  // The original description
  
  1) The release of Ubuntu you are using, via 'lsb_release -rd' or System -> 
About Ubuntu
  root@ubuntu1404:~# lsb_release -rd
  Description:    Ubuntu 14.04.1 LTS
  Release:        14.04
  
  2) The version of the package you are using, via 'apt-cache policy pkgname' 
or by checking in Software Center
  root@ubuntu1404:~# apt-cache policy bash-completion
  bash-completion:
    Installed: 1:2.1-4
    Candidate: 1:2.1-4
    Version table:
   *** 1:2.1-4 0
          500 http://se.archive.ubuntu.com/ubuntu/ trusty/main i386 Packages
          100 /var/lib/dpkg/status
  
  3) What you expected to happen
  
  When I use bash-completion it should not read the /etc/passwd file or contact 
the Active directory.
  It is very hard to see this problem unless you run this on a machine with 
slow authentication... but the commands below will show if the /etc/passwd or 
sssd are used by bash_completion or not:
  
  root@ubuntu1404:~# strace bash -c ". /etc/bash_completion; quote_readline 
'/something'; echo" 2>&1 | grep /etc/passwd
  root@ubuntu1404:~# strace bash -c ". /etc/bash_completion; quote_readline 
'/something'; echo" 2>&1 | grep sss
  
  When the ~ are escaped on line 545 and 547 in /usr/share/bash-
  completion/bash_completion then bash_completion works as expected.
  
  4) What happened instead
  
  Every time you use tab-completion in bash on ubuntu 14.04 it will read
  the /etc/passwd file and if sssd are installed and configured for Active
  Directory authentication it will talk to sssd... and this can be slow in
  some environments.
  
  root@ubuntu1404:~# strace bash -c ". /etc/bash_completion; quote_readline 
'/something'; echo" 2>&1 | grep /etc/passwd
  open("/etc/passwd", O_RDONLY|O_CLOEXEC) = 3
  root@ubuntu1404:~# strace bash -c ". /etc/bash_completion; quote_readline 
'/something'; echo" 2>&1 | grep sss
  open("/lib/i386-linux-gnu/libnss_sss.so.2", O_RDONLY|O_CLOEXEC) = 3
  open("/var/lib/sss/mc/passwd", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = 3
  connect(4, {sa_family=AF_LOCAL, sun_path="/var/lib/sss/pipes/nss"}, 110) = 0
  
  I have made a small patch for this problem and I have not found any side 
effects:
  --- /usr/share/bash-completion/bash_completion.orig     2014-11-06 
10:36:14.981888369 +0100
  +++ /usr/share/bash-completion/bash_completion  2014-11-06 10:36:25.142070963 
+0100
  @@ -542,9 +542,9 @@
       elif [[ $1 == \'* ]]; then
           # Leave out first character
           printf -v $2 %s "${1:1}"
  -    elif [[ $1 == ~* ]]; then
  +    elif [[ $1 == \~* ]]; then
           # avoid escaping first ~
  -        printf -v $2 ~%q "${1:1}"
  +        printf -v $2 \~%q "${1:1}"
       else
           printf -v $2 %q "$1"
       fi

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https://bugs.launchpad.net/bugs/1390061

Title:
  bash-completion tilde expansion every time

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