Merge pull request #3567 from mcornella/bsandrow-topic/virtualenvwrapper-ubuntu

Repost #2819: fix virtualenvwrapper for Ubuntu and Debian

plugins/virtualenvwrapper/virtualenvwrapper.plugin.zsh

 virtualenvwrapper='virtualenvwrapper.sh'
-if (( $+commands[$virtualenvwrapper] )); then
 
+if (( $+commands[$virtualenvwrapper] )); then
   source ${${virtualenvwrapper}:c}
+elif [[ -f "/etc/bash_completion.d/virtualenvwrapper" ]]; then
+  virtualenvwrapper="/etc/bash_completion.d/virtualenvwrapper"
+  source "/etc/bash_completion.d/virtualenvwrapper"
+else
+  print "zsh virtualenvwrapper plugin: Cannot find ${virtualenvwrapper}.\n"\
+        "Please install with \`pip install virtualenvwrapper\`" >&2
+  return
+fi
+if ! type workon &>/dev/null; then
+  print "zsh virtualenvwrapper plugin: shell function 'workon' not defined.\n"\
+        "Please check ${virtualenvwrapper}" >&2
+  return
+fi
 
-  if [[ "$WORKON_HOME" == "" ]]; then
-    echo "\$WORKON_HOME is not defined so ZSH plugin virtualenvwrapper will not work"
-  else
+if [[ "$WORKON_HOME" == "" ]]; then
+  print "\$WORKON_HOME is not defined so ZSH plugin virtualenvwrapper will not work" >&2
+  return
+fi
 
-    if [[ ! $DISABLE_VENV_CD -eq 1 ]]; then
+if [[ ! $DISABLE_VENV_CD -eq 1 ]]; then
   # Automatically activate Git projects's virtual environments based on the
   # directory name of the project. Virtual environment name can be overridden
   # by placing a .venv file in the project root with a virtualenv name in it
@@ -50,16 +64,7 @@ if (( $+commands[$virtualenvwrapper] )); then
 
   # Append workon_cwd to the chpwd_functions array, so it will be called on cd
   # http://zsh.sourceforge.net/Doc/Release/Functions.html
-      # TODO: replace with 'add-zsh-hook chpwd workon_cwd' when oh-my-zsh min version is raised above 4.3.4
-      if (( ${+chpwd_functions} )); then
-        if (( $chpwd_functions[(I)workon_cwd] == 0 )); then
-          set -A chpwd_functions $chpwd_functions workon_cwd
-        fi
-      else
-        set -A chpwd_functions workon_cwd
+  if ! (( $chpwd_functions[(I)workon_cwd] )); then
+    chpwd_functions+=(workon_cwd)
   fi
-    fi
-  fi
-else
-  print "zsh virtualenvwrapper plugin: Cannot find ${virtualenvwrapper}. Please install with \`pip install virtualenvwrapper\`."
 fi